Cach dung Could have

Could Have
We can use `could have`  to talk about something somebody was capable of doing but didn`t do.
I could have gone to Oxford University but I preferred Harvard.
She could have married him but she didn`t want to.
They could have bought a house here 20 years ago but chose not to.
Often, there is a sense of criticism.
You could have phoned me to let me know.
They could have helped me instead of just sitting there.
 I could have done more to help you. Sorry.
We can use `couldn`t have` to talk about something we were not capable of doing.
I couldn`t have managed without you.
I couldn`t have got the job. He was always going to appoint his nephew.
I couldn`t have enjoyed myself more. Thank you for a lovely day.
We can use `could have` to speculate about what has happened. (We can also use `may have` or `might have` in these situations.)
She could have taken the earlier train.
Simon could have told her.
They could have overheard what we said.
We can also use `can have` to speculate about what has happened but only in questions and negative sentences and with words such as `hardly`, `never` and `only`.
Can she have forgotten about our meeting?
He can`t have seen us.
They can hardly have thought that I was not interested in the job.
We can also use `could have` to speculate about something that didn`t happen.
You could have broken your neck, jumping out the window like that.
He could have hurt somebody, throwing a bottle out of the window like that.
I could have done well in my exam if I`d worked harder.
You can also use `could have` to talk about possible present situations that have not happened.
I could have been earning a lot as an accountant but the work was just too boring.
He could have been Prime Minister now but he got involved in a big financial scandal.
They could have been the market leaders now if they had taken his advice.