When he ______the door, he found his keys were nowhere.
| A．would open | B．opened |
| C．had opened | D．was to open |
一Could you tell me what happed last night ?
一I can't go into detail now because it _______ take too long.
| A．would | B．should | C．might | D．could |
— Mummy, I have broken my train.
一I told you so. You _______ on it.
| A．mustn't have ridden | B．couldn't ride |
| C．shouldn't have ridden | D．needn't ride |
You can't imagine that a top student ______ have failed in the college entrance examination.
| A．might | B．need | C．should | D．would |
Thank you for giving me a hand. I ______ in the experiment without your valuable help.
| A．have failed | B．will fail | C．would have failed | D．must have failed |
This cake is very sweet. You _____ a lot of sugar in it.
| A．should put | B．could have put | C．might put | D．must have put |