— I must apologize for ________ ahead of time.
— That's all right.
| A．letting you not know | B．not letting you know. |
| C．letting you know not | D．letting not you know |
Mr. Smith couldn’t open the door because his naughty boy _______ it from the inside
| A．would lock | B．was locking | C．has locked | D．had locked |
I know little about the accident because not much_________ about it up to now
| A．has said | B．has been said | C．had said | D．had been said |
I’ve been away for only three years, _____ I can hardly recognize my hometown
| A．so | B．or | C．for | D．yet |
In China, you _____ vote when you are 18.
| A．must | B．might | C．can | D．would |
The professor could hardly find sufficient grounds _____his arguments in favor of the new theory.
| A．to be based on | B．to base on |
| C．which to base on | D．on which to base |