simile
noun
(the use of) an expression comparing one thing with another; the use of ‘as’ or ‘like’
She described her child’s dirty face using the simile “as black as coal”. [C]
The lines ‘She walks in beauty, like the night…’ from Byron’s poem contain a simile. [C]
The poem was rich in simile. [U]

Basically, we use the expression as + adjective/adverb + as when we want to say that two things are the same in some way:
Do you think they are as good as they say?
I’m just as capable as you are – let me do it!
The weather’s as miserable as usual.

Note that we can also use as + adjective/adverb + as (or so + adjective/adverb + as) after the word not in negative expressions:
They are not as/so good as they say they are.
You’re not as/so capable as I am – let me do it!
The weather’s not as/so miserable as usual.

Similes with as + adjective/adverb + as are used in many “set” expressions commonly used by native speakers when comparing things:
Some of these monuments are as old as the hills.
The floor’s as clean as a whistle.
Little Jane’s as quiet as a mouse – I wonder what she’s up to.
That shower’s made me feel much better – as fresh as a daisy.

As a learner of English, you might not feel very comfortable using this type of expression. In this case, you should feel free to invent your own similes, as long as the comparisons are valid ones. For example, English speakers say “as white as a sheet” because, traditionally anyway, sheets were usually white. A learner might prefer “as white as snow”, or “as white as cotton wool”, and these are good “invented similes” because the image in people’s minds of snow and cotton wool is of whiteness.

Depending on what sort of information we want, we use one of the following question words:
Who wrote that book? (person)
What is your name? (thing)
Which book is yours? (thing) – see below
When did you arrive? (time)
Where do you live? (place)
Why are you doing that? (reason)
How can I find out? (manner)

What and which can often be used with the same meaning. When the person asking the question has a restricted number of choices in mind, s/he will use which. When s/he is not thinking of a restricted number of choices, what is used:
Which main course (from the menu) are you going to have?
Which department (of this company) do you work in?
What name is on the envelope?
What number shall I call?

Whom is a more formal way of saying who, and is not common when speaking. If we choose to put our question word after a preposition, then we must use whom:
With whom did you go?

However, this is very unusual, and we would normally avoid this by putting the preposition at the end of the phrase:
Who did you go with?

Apart from these single words, we combine two or more words to find out other kinds of information:
How old are you?
What time is it?
How many children have you got?
How long did it take?

Question tags are the short questions that we put at the end of sentences, especially in spoken English.
You’re coming, aren’t you?
He’s not serious, is he?

If the main part of the sentence is affirmative, then the question tag is negative:
It’s warm, isn’t it?
They went also, didn’t they?

If the main part of the sentence is negative, then the question tag is affirmative:
She couldn’t see it, could she?
We won’t know till tomorrow, will we?

If the main part of the sentence contains an auxiliary verb (or the verb “to be”, then this is used in the question tag:
They are away for a few days, aren’t they?
You weren’t available, were you?
She’s Mexican, isn’t she?
It wasn’t his turn, was it?
You’ve got a cat, haven’t you?
He’s got a new house, hasn’t he?
We can’t go in there, can we?
They couldn’t hear me, could they?

If the main part of the sentences does not contain an auxiliary verb, then we use the verb “to do” in the question tag:
She needs some help, doesn’t she?
He loved his work, didn’t he?
You come here often, don’t you?

Depending on what we wish to say, the intonation of a question tag is different. If we are asking a real question (in other words, if we don’t know the answer), then our voice rises on the question tag:
That’s spelt with two n’s, isn’t it?

On the other hand, if we are sure of the answer and are only asking for agreement, our voice falls on the question tag:
It’s your turn next, isn’t it?

A part of speech (also word class) is any of the grammatical groups into which words are divided depending on their use.

The following are the different parts of speech in English grammar:

Adjective
A word that describes a noun or pronoun. ‘
‘Big’, ‘boring’, ‘purple’, ‘quick’, ‘obvious’ and ’silvery’ are all adjectives.

Adverb
A word which describes or gives more information about a verb, adjective, adverb or phrase.

In the following sentences, ‘cheerfully’, ’spotlessly’, ‘extremely’, ‘well’, and ‘right’ are adverbs:
She smiled cheerfully.
The house was spotlessly clean.
He’s managing extremely well.
The shot was heard right outside the door.

Conjunction
A word such as ‘and’, ‘but’, ‘while’ or ‘although’ that connects words, phrases and clauses in a sentence.

Determiner
A word which is used before a noun to show which particular example of the noun you are referring to.
In the phrases ‘my first boyfriend’ and ‘that strange woman’, the words ‘my’ and ‘that’ are determiners.

Interjection
An interjection is a word which is used to show a short sudden expression of emotion.
“Hey!” is an interjection.

Noun
A word that refers to a person, place, thing, event, substance or quality.
‘Doctor’, ‘tree’, ‘party’, ‘coal’ and ‘beauty’ are all nouns.

A noun phrase is a group of words in a sentence which together behave as a noun.
In the sentences ‘We took the night train’ and ‘Do you know the man sitting in the corner’, ‘the night train’ and ‘the man sitting in the corner’ are noun phrases.

Preposition
A word which is used before a noun, a noun phrase or a pronoun, connecting it to another word.
In the sentences, ‘We jumped in the lake’, ‘There were cheers at the end of the performance’ and ‘She drove slowly down the track’, ‘in’, ‘at’, ‘of’ and ‘down’ are prepositions.

Pronoun
A word which is used instead of a noun or a noun phrase.

Pronouns are often used to refer to a noun that has already been mentioned.
‘She’, ‘it’ and ‘who’ are all examples of pronouns.

Verb
A word or phrase that describes an action, condition or experience.
The words ‘run’, ‘keep’ and ‘feel’ are all verbs.

When adding an ending to a word that ends with y, change the y to i when the y comes after a consonant:
Fairy – Fairies
Carry – carries
Carry – carried
Empty – emptiness
Marry – marriage
Easy – easily
Lucky – luckier

If the ending you want to add begins with the letter i the y does not change, e.g. – ing, – ish, – ism
Carry – carrying
Thirty – thirtyish
Crony – cronyism

When adding an ending to a word that ends with y, make no change if the y comes after a vowel:
Pay – paying
Obey – obeyed
Toy – toying
Buy – buying

Note the following exceptions to this rule:
Say – said
Pay – paid
Lay – laid

When adding an ending to a word that ends with ie, change the ie to y before -ing:
Lie – lying
Die – dying
Tie – tying

Briefly, we can say that apostrophes have three uses:

1) To show possession in nouns

We add an apostrophe and “s” after all singular nouns and after plural nouns that do not end in “s”:
Susan’s book; Pete’s dog; the children’s toys; the men’s room.

We add an apostrophe without “s” after plural nouns ending in “s”:
The Beckhams’ mansion; the dogs’ dinners.

Note that we do not use apostrophes with the possessive pronouns hers, its, ours and yours, but we do use them with possessive pronouns that end in “-one” or “-body”:
Give the cat its dinner; Those books are ours.
It must be somebody’s; Everyone’s papers are on the table.

2) To represent missing letters

We use apostrophes in contractions like:
Didn’t (Did not); There’s (There is); We’ll (We will)

(3) In some plural forms

Some sources (e.g. Practical English Usage, Michael Swan, Oxford University Press, 1997) indicate that we can use apostrophes if we want to make a plural form of a noun that does not normally have one:
I am afraid there are too many if’s and but’s for me to approve the plan.

The same source suggests that they can also be used in the plurals of letters, and with abbreviations and numbers:
The manager crossed the t’s and dotted the i’s of the document.
The 1990’s were very exciting years (also 1990s).

Other sources (e.g. Apostrophe Protection Society), however, indicate that apostrophes have no place in plurals because they do not represent missing letters or possession, and that the examples above should be written:
I am afraid there are too many IFs and BUTs for me to approve the plan.
The manager crossed the Ts and dotted the Is of the document.
The 1990s were very exciting years.

The same source points out that this sort of use is more appropriate to spoken English than written English, and that in the latter the best option would be to write the sentences in a different way in order to avoid the use of apostrophes:
I am afraid there are too many uncertainties for me to approve the plan.
The manager corrected / approved the document.

“Some words in English have silent letters. How can we know which letters in which words are silent?”

Unfortunately, the best answer to this question is “Become a professional etymologist!” Etymology is the study of the origins of words, and the truth is that this is more a question of etymology than of grammar.

To give an idea of how big an area we are considering here, according to Kent Jones, Education Committee, Esperanto Society of Chicago, “More than 60% of (English) words have silent letters.”

James Chandler observes “Many people are perhaps not aware of the astonishing fact that nearly every letter of the English alphabet is silent in some word.”

Here are three reasons why English has so many silent letters:

Old English was 90% phonemic (words sound the same as they look). But from the beginning of the 15th century, we began to borrow words from other languages. Because grammar and usage rules are different in other languages, adopted words did not follow the rules of English pronunciation.

The English language ‘borrowed’ the Latin alphabet, and so we have only got 26 letters to represent around 41 different significant sounds. This means that we must attempt to use combinations of letters to represent sounds.

In the Middle English Period William Caxton brought the printing press to England. As time passed, pronunciation continued to change, but the printing press preserved the old spelling. That’s why today we have words that end in a silent ‘e’, or have other silent letters in the middle, like ‘might’. In fact, modern day English is only 40% phonemic.

So are there any rules and can they help us? Axel Wijk (Regularized English, 1959, Stockholm: Almqvist & Wiksells) came up with over 100 rules for English spelling. It is claimed that by using these rules, you can spell up to 85% of the words in English with 90% accuracy. But is this really helpful? Basically, no! It gets so complicated that a much easier approach is to memorize sight words.

So you can see that unfortunately there is no clear way to know about all the silent letters in English. But is it a hopeless case? Well, the best we can do is to offer the following list of some silent letters:
Mb at the end of a word (silent b), e.g. comb, lamb, climb.
Sc at the beginning of a word followed by ‘e’ or ‘i’, (silent c), e.g. scene, scent, science, scissors (except for the word ’sceptic’ and its derivations!).
Kn (silent k), e.g. knife, knock, know.
Mn at the end of a word (silent n), e.g. damn, autumn, column
Ps at the beginning of a word (silent p), e.g. psalm, psychiatry, psychology
Ght (silent gh), e.g. night, ought, taught
Gn at the beginning of a word (silent g), e.g. gnome, gnaw, gnu
Bt (silent b), e.g. debt, doubtful, subtle (but not in some words, e.g. ‘obtain’, ‘unobtrusive’!)

The letter H is silent in the following situations:
At the end of word preceded by a vowel, e.g. cheetah, Sarah, messiah;
Between two vowels, e.g. annihilate, vehement, vehicle
After the letter ‘r’, e.g. rhyme, rhubarb, rhythm
After the letters ‘ex’, e.g. exhausting, exhibition, exhort.

Indirect questions can refer to two different things:
Questions in reported speech
Questions within questions

Questions in reported speech

When we report questions, we use the word order of an affirmative statement. In other words, the subject usually comes before the verb, and the auxiliary “do” is not used.

Tense and time changes are the same as for other types of reported speech (see grammar definitions: reported speech).

We use “if” or “whether” to report “yes/no” questions.

We do not put a question mark at the end of reported questions.
What do you like doing in your free time?
He asked me what I liked doing in my free time.
Are you going to the film tomorrow?
She asked if/whether we were going to the film the next day.

Questions within questions

We sometimes avoid asking direct questions to people, especially if we wish to be polite. In more formal speech, this type of structure is quite common.
Do you know if/whether she is coming with us?
Could you tell me when the film begins?
Would you be so good as to tell me if the Director has arrived yet?

They are “questions within questions” because although we are asking, for example, “Do you know? “, we really want some other information.

Notice that in the “Do you know …”, “Could you tell me …”, etc., part of the question, the auxiliary verb, e.g. “do” or “could”, comes before the subject. In the “real” question, however, the same word order rules apply as for questions in reported speech. Finally, we must put a question mark at the end.

English vowels can be pronounced differently, having both short and long sounds:
Fat (short)
Fate (long)
Equate (short)
Equal (long)
Dinner (short)
Diner (long)
Hop (short)
Hope (long)
But (short)
Butane (long)

We double the final consonant of a word before we add -ed, -er, -est, -ing, -able and -y to show that the vowel has a short sound.

But how do you know when to double the consonant and when not to? There are a number of things to consider.

Firstly, we only double a consonant if it comes at the end of at word.
Slop – slopped – slopping BUT slope – sloped – sloping

Secondly, we only double a consonant if a word ends in one vowel followed by one consonant.
Dig – digging
Shut – shutting

BUT
Fool – fooled – fooling
Bend – bending

Thirdly, we need to consider words that end in one vowel followed by one consonant, but contain two syllables. We only double the consonant in these words if the last syllable is stressed:

Last syllable stressed
Deter – deterred – deterring
Unplug – unplugged – unplugging

Last syllable unstressed
Happen – happened – happening
Gather – gathered – gathering

Note: in two syllable words ending in one vowel followed by one “l”, the “l” is doubled even if the last syllable is unstressed:
Travel – travelled – travelling

Fourthly, only some letters are doubled.
B – rob – robbed – robbing
D – bid – bidded – bidding
G – dig – digging
L – travel – travelled – travelling
M – swim – swimming
N – plan – planned – planning
P – shop – shopped – shopping
R – deter – deterred – deterring
T – bet – betted – betting

The web sites linked to below provide thorough explanations of the use of all of these elements of punctuation.

Commas
My favourite sports are cricket, athletics, football and archery.
It is a costly, inefficient, outdated transport system.
Hewitt, who beat Kafelnikov in the semi-final, plays Sampras today.
When you finally make a decision, let me know.
634, 567, 981

http://stipo.larc.nasa.gov/sp7084/sp7084ch3.html#3.5

Colons
The children have been grounded: they ruined the rose garden while we were out.
LORD POLONIUS: I hear him coming: let’s withdraw, my lord.
HAMLET: To be, or not to be: that is the question.
The following items are required: paper, pens, pencils, pencil sharpeners and rubbers.
Grammar: punctuation

http://stipo.larc.nasa.gov/sp7084/sp7084ch3.html#3.4

Semi-colons
I am very keen on parachuting; Tim prefers hang-gliding.
All passengers have been informed that they must not carry sharp objects; that random spot-checks can be expected; that longer than usual delays are possible.

http://stipo.larc.nasa.gov/sp7084/sp7084ch3.html#3.15

Dashes
Here are some of my favourite things – picnics, sunbathing, and sleeping in.
They won’t be in this morning – they have a meeting with the director.
Our last car – which was a Ford – only ever broke down once.