Children under 12 years of age in that country _________ be under adult supervision（监管）when in a public library.
| A．must | B．may | C．can | D．need |
---David has made great progress recently.
--- _____, and _____.
| A．So he has; so you have | B．So he has; so have you |
| C．So has he; so have you | D．So has he;so you have |
____ is no good ____ without doing anything.
| A．This; talking | B．It; to talk | C．It; talking | D．That; to talk |
I am not ______ up late.
| A．accustomed staying | B．accustomed to staying |
| C．used to stay | D．addicted to stay |
If we don't start now, we must risk ____ the train.
| A．being missed | B．missing | C．to miss | D．miss |
If I ______ten years younger, I _____ very happy.
| A．am, would be | B．am, shall be | C．were, shall be | D．were, would be |