49. ____ and friends should be few but good. (prov.)
| A．Money | B．Jobs | C．Books | D．Interests |
A computer can only do ________ you have instructed it to do.
| A．how | B．after | C．what | D．when |
—If he ___________, he ________that food.
—Luckily he was sent to the hospital immediately.
| A． was warned; would not take | B．had been warned; would not have taken |
| C．would be warned; had not taken | D．would have been warned; had not taken |
When a pencil is partly in a glass of water, it looks as if it _______.
| A． breaks | B．has broken | C．were broken | D．had been broken |
One learns a language by making mistakes and _______ them.
| A． correct | B．correcting | C．corrects | D．to correct |
_____such heavy pollution already, it may now be too late to clean up the river.
| A． Having suffered | B．Suffering | C．To suffer | D．Suffered |