Using 'could have' you are speaking about something that was, should be or would be. You are stating that they had other options that could have been chosen.

使用'could have'你说的是，应该是或者是，你表明他们应该还有其他的选择。

Here are some examples: 这里有一些例子： 

"You could have completed it sooner."

 你本来可以早点完成的。

"You could have blown your chance."

 你可能会错过机会。

"You could have done better on your exam."

 你本来可以考得更好的。

"You could have given me more time to get ready."

 你本可以给我更多时间准备的。

"You could have heard that from someone else."

 你本可以从别人那里听到的。

"You could have sent that package first class."

 你本来可以把那个包裹寄头等舱的。

"You could have slept in a little longer."

 你本可以睡得更长一些。

"You could have written him a letter."

 你本可以给他写封信的。

"You could have thought of something to do."

 你本可以考虑做点什么的。

"You could have upset her by saying that."

 你这样说可能会让她不高兴。