单项选择（每题1分）
He often speaks of the trouble he _______ to help the orphan.
| A．had | B．found | C．made | D．took |
——-Shall we go out for a walk?
——Sorry. This is not the right ____ to invite me. I am too tired to walk.
| A．moment | B．situation | C．place | D．chance |
It is clear that the whole world is passing through a social revolution in which a central _____ must be taken by scientists and technologists.
| A．process | B．attention | C．measure | D．part |
The author of the report is well _____ with the problems in the hospital because he has been working there for many years.
| A．acquainted | B．informed | C．enlightened | D．advised |
With the change of the economic foundation the entire immense superstructure is _____ rapidly transformed.
| A．anything but | B．more or less | C．at large | D．any more |
Even if they are on sale, these refrigerators are equal in price to, if not more expensive than, _____ at the other store.
| A．anyone | B．the others | C．that | D．the ones |