. He must be curious about everything in the lab, for this/that/it is the first time that he has been there, ________?
| A．isn’t he | B．mustn’t | C．isn’t it | D．hasn’t he |
you may have , you should gather your courage to face the challenge .
| A．However serious a problem |
| B．Whatever serious a problem |
| C．However a serious problem |
| D．No matter how a serious |
He was seriously injured．He lay on the ground, _______ to stand up．
| A．was unable | B．being not able |
| C．unable | D．being able not |
---Thanks for your help, but can you do me one more favor, please?
---____ , sir. What’s it then?
| A．Just a minute | B．At your service |
| C．That’s right | D．It’s my pleasure |
He is a man of few words, and seldom speaks until _______ to.
| A．speaking | B．spoken | C．speak | D．be spoken |
-- May I smoke here?
-- If you____, that's the smoking section over there.
| A．should | B．could | C．may | D．must |