Lista das principais contrações usadas na Língua Inglesa

Contraction	Meaning
ain't (1)	am not; are not; is not; has not; have not
aren't (2)	are not; am not
can't	cannot
can't've	cannot have
'cause	because
could've	could have
couldn't	could not
couldn't've	could not have
didn't	did not
doesn't	does not
don't (3)	do not
hadn't	had not
hadn't've	had not have
hasn't	has not
haven't	have not
he'd	he had / he would
he'd've	he would have
he'll	he shall / he will
he'll've	he shall have / he will have
he's	he has / he is
how's	how has / how is
I'd	I had / I would
I'd've	I would have
I'll	I shall / I will
I'll've	I shall have / I will have
I'm	I am
I've	I have
isn't	is not
it'd	it had / it would
it'd've	it would have
it'll	it shall / it will
it'll've	it shall have / it will have
it's	it has / it is
let's	let us
ma'am	madam
might've	might have
mightn't	might not
mightn't've	might not have
must've	must have
mustn't	must not
mustn't've	must not have
o'clock	of the clock
oughtn't	ought not
oughtn't've	ought not have
shan't (4)	shall not
shan't've	shall not have
she'd	she had / she would
she'd've	she would have
she'll	she shall / she will
she'll've	she shall have / she will have
she's	she has / she is
should've	should have
shouldn't	should not
shouldn't've	should not have
so's	so as / so is
that's	that has / that is
there'd	there had / there would
there's	there has / there is
they'd	they had / they would
they'll	they shall / they will
they'll've	they shall have / they will have
they're	they are
they've	they have
wasn't	was not
we'd	we had / we would
we'll	we will
we'll've	we will have
we're	we are
we've	we have
weren't	were not
what'll	what shall / what will
what'll've	what shall have / what will have
what're	what are
what's	what has / what is
what've	what have
when's	when has / when is
when've	when have
where'd	where did
where's	where has / where is
where've	where have
who'll	who shall / who will
who'll've	who shall have / who will have
who's	who has / who is
who've	who have
why's	why has / why is
will've	will have
won't	will not
won't've	will not have
would've	would have
wouldn't	would not
wouldn't've	would not have
y'all'd've	you all would have
you'd	you had / you would
you'd've	you would have
you'll	you shall / you will
you'll've	you shall have / you will have
you're	you are
you've	you have
Substantivo seguido por  's	"noun is" or "noun has"

Notes

1. "ain't"  é usado como contração de muitos verbos, mas é considerada uma maneira informal demais, não devendo ser usada em situações mais formais, como em relações de trabalho, por exemplo.
2. "aren't" normalmente é usado como contração de  "are not"; entretanto, é comum ser usado novemente como contração de "am not" in perguntas (exemplo:  "Aren't I the greatest?").
3. "don't" as vezes é usado no lugar de "does not", no inglês, porém é importante frisar que gramaticalmente, isto é incorreto.
4. Algumas vezes pronunciado como "sha'n't," principally quanto usado junto de verbos mais antigos.

Alguns exemplos:
I'm --- I am --- Example: I'm waiting for my friend.
I'll --- I will --- Example: I'll see you tomorrow.
I'd --- I had / I would --- Example: I'd better leave now. OR I'd already eaten by the time he arrived.
I've --- I have --- Example: I've worked here for many years.
You're --- You are --- Example: You're joking!
You'll --- You will --- Example: You'll be sorry!
You'd --- You had / would --- Example: You'd left before he arrived, hadn't you? OR You'd better hurry up.
You've --- You have --- Example: You've been to London many times.
He's --- He is / has --- Example: He's on the phone now. OR He's been playing tennis since 10 this morning.
He'll --- He will --- Example: He'll be here tomorrow.
He'd --- He had / would --- Example: He'd prefer to meet you later in the week. OR He'd finished before the meeting began.
She's --- She is / has --- Example: She's watching TV at the moment. OR She's had a lot of trouble lately.
She'll --- She will --- Example: She'll be at the meeting.
She'd --- She had / would --- Example: She'd been working for two hours when he telephoned. OR She'd like to have a glass of wine.
It's --- It is / has --- Example: It's been long time since we saw each other last. OR It's very difficult to concentrate.
It'll --- It will --- Example: It'll be here soon.
It'd --- It would / had --- Example: It'd be difficult to say no. OR It'd been a long time.
We're --- We are --- Example: We're working hard on the Smith account this week.
We'll --- We will --- Example: We'll begin when he arrives.
We'd --- We had / would --- Example: We'd better hurry up if we want to catch the train. OR We'd finished the meeting before you arrived.
We've --- We have --- Example: We've been waiting for you!

They're --- They are --- Example: They're studying German this afternoon.
They'll --- They will --- Example: They'll finish soon if they concentrate.
They'd --- They had / would --- Example: They'd eaten their lunch when she stopped by to say hello. OR They'd rather not come to the meeting.
They've --- They have --- Example: They've just purchased a new home.
There's --- There is / has --- Example: There's a hotel in the next town. OR There's been too many telephone calls today!
There'll --- There will --- Example: There'll be a price to pay!
There'd --- There had / would --- Example: There'd better be a good explanation for this. OR There'd be some reason for that.
That's --- That is / has --- Example: That's been on my mind lately. OR That's why I can't come.
That'll --- That will --- Example: That'll happen sooner than you think.
That'd --- That had / would --- Example: That'd be the reason why. OR That'd happened before my time.
Negative Contractionsaren't --- are not --- Example: They aren't coming next week.
can't --- can not --- Example: I can't understand you.
couldn't --- could not --- Example: He couldn't get his shoes on!
didn't --- did not --- Example: We didn't visit Rome. We went straight to Florence.
doesn't --- does not --- Example: He doesn't play golf.
don't --- do not --- Example: They don't like cheese.
hadn't --- had not --- Example: I hadn't thought of that!
hasn't --- has not --- Example: She hasn't telephoned yet.
isn't --- is not --- Example: She isn't listening to you.
mustn't --- must not --- Example: Children mustn't play with fire.
needn't --- need not --- Example: You needn't worry about that.
shouldn't --- should not --- Example: You shouldn't smoke cigarettes.
wasn't --- was not --- Example: I wasn't joking when I said that.
weren't --- were not --- Example: They weren't invited to the party.
won't --- will not --- Example: I won't be able to attend the conference.
wouldn't --- would not --- Example: She wouldn't be surprised if he showed up at the party.

Aqui está um quadro com mais alguns exemplos:  

Auxiliary Form	Contractions With Pronouns	Contractions With Nouns	Contractions With Question Words
am	I'm working this morning.	-	What'm I supposed to say? (common only in spoken English)
is	He's going to come. - She's a teacher. - It's easy!	John's at work. - Mary's playing the piano at the moment.	Who's on the telephone? - What's he doing?
are	You're a great friend! - They're playing golf this afternoon.	The books're on their way. (common only in spoken English)	What're you going to do?
has	He's been to Paris twice. - It's been such a long time! - She's lived there all her life.	Mary's gone to the store.	What's she been doing? - Who's been invited?
have	I've finished my homework. - They've got two cars.	The students've finished their homework. (common only in spoken English)	Where've you been all day? (common only in spoken English)
had	He'd been waiting for three hours. - We'd better be going.	Jack'd worked there before he left. (common only in spoken English)	What'd you done before that? (common only in spoken English)
will	I'll get you something to eat. - We'll be there soon.	Peter'll catch the bus to work.	What'll we do? Where'll you take us?
would	I'd like some fish. They'd love to ask you some questions.	Jane'd love to come.	Where'd you like to go? (common only in spoken English)