Hi cleung
.
Generally speaking, you should
not end a sentence with a contraction of a
verb and a
noun or pronoun.
(
I'm, you're, he's, she's, it's, we're, they're, I've, you've, we've, they've, I'd, he'll, etc.)
.
You
cannot say:
Do you know who I'm?
.
Instead you say things such as:
Do you know who I am?
Do you know how many kids John has?
Can you tell me where they are?
Yes, I will.
.
.
Especially in
spoken English, you'll hear sentences such as these ending with a contraction of
have and another verb and/or the word
not:
=>
Now that you mention it, I think he must've. (...he must have done that)
=>
You shouldn't've!
.
It's OK to end a sentence with a contraction of a verb and the word
not:
=>
No, he isn't.
.