18．T appreciate that it's not easy for you, but you ______ try to get here on time．
| A．may | B．must | C．will | D．Can |
The new buyer identified a dozen new sources for the material, ___________ proved to be reliable．
| A．most of them | B．most of which | C．most of whom | D．most of those |
_____ I say Clancy is a smart boy, he still needs to work hard to achieve his goal.
| A．Then | B．When | C．While | D．As |
Unfortunately, ____ stone hit him on ______ head and he got injured.
| A．the; a | B．a; 不填 | C．a; the | D．the; the |
____ to Anne's birthday party, Mr. Brown is now searching shop after shop for a nice present for her.
| A．Having invited | B．Having been invited | C．Have been invited | D．Being invited |
The activities organized by our school really gave us a platform ____ we learned team spirit.
| A．that | B．where | C．which | D．when |