Hi teachers,<br/><br/>What is the difference between "couldn't have finished" and "can't have finished"?<br/><br/>Here are two examples:<br/><br/>A wealthy businessman donated a considerable amount of money to our project; otherwise, we <u><b>couldn't have finished</b></u> it.<br/><br/>A wealthy businessman donated a considerable amount of money to our project; otherwise, we <u><b>can't have finished</b></u> it.<br/><br/>Thank you.