The conference has been held to discuss the effects of tourism ______ the wildlife in 
the area.
| A．in | B．on | C．at | D．with |
---Why did you leave that position?
---I a better position at IBM.
| A．offer | B．offered | C．am offered | D．was offered |
--Have you got the leaving time of the train for me?
---Yes, but you’d better ____of it by yourself.
| A．make sure | B．be sure | C．to make sure | D．be certain |
Jumping out of ______ airplane at ten thousand feet is quite ______ exciting experience.
| A．/; an | B．/; the | C．an; an | D．the; the |
What do you think ____________ at this time last night?
| A．has he done | B．he has done | C．was he doing | D．he was doing |
I’ll show you a store __________ you may buy all ___________ you need.
| A．where; which | B．in which; that | C．which; that | D．that; that |