____ students have graduated from this school in the last twenty years.
| A．Tens of thousands of | B．Tens upon thousands of |
| C．Tens in thousands | D．Ten thousands of |
Polar bears live mostly on __________ sea ice, which they use as __________ platform for hunting seals.
| A．a; a | B．a; the | C．不填; a | D．the; 不填 |
Is it John that is being scolded in the manager’s office?
No. It ______ be him. I saw him on the way just now.
| A．mustn’t | B．won’t | C．can’t | D．may not |
The question came up at the meeting_____ we had enough money for our research．
| A．that | B．which | C．whether | D．if |
Twenty of the students will have sports, the rest ___ studying here
| A．are | B．is | C．were | D．was |
He is a strict but kind-hearted father, ____ the children respect but are afraid of.
| A．/ | B．that | C．for whom | D．one whom |