I often go to school ________.

Mistakes don’t just happen; they occur for a reason. Find out the reason, and then making the mistake becomes _________.[ ]

ore and more important to protectour earth.—-I think so. If everyone ______acontribution to it, our world will be more beautifu..

.In an effort to maintain social balance, the Chinese government several years ago _______a policy of encouraging college graduates to take official positions in rural areas.

The old men can hardly imagine that they can live in an age _______ most of the daily things are done on the computers.