The professor managed to find some grounds (facts)_________his arguments．
| A．to be based on | B．to base on |
| C．which to base on | D．on which are based |
I longed to have the opportunity of ______ your activities.
| A．joining | B．playing |
| C．taking part in | D．attending to |
The poor had to ______ a living.
| A．struggle against | B．struggle for |
| C．struggle on | D．struggle with |
Without facts, we can't form a worthwhile opinion, for we need to have factual knowledge ______ our thinking.
| A．which to be based on | B．upon which to base |
| C．which to base upon | D．to which to be based |
With the government's aid, those ______ by the earth-quake have moved to the new settlement.
| A．affect | B．affecting |
| C．affected | D．to be affected |
Mrs White showed her students some old maps ______ from the library.
| A．to borrow | B．to be borrowed |
| C．borrowed | D．borrowing |