When a spacecraft travels, one of the major problems is reentry into the Earth ’s _______.

John _______ to be a polite man. But in fact he is veryrude.

This river forms a natural _______ between China and Korea.

We can not trust him any more because he often________ his duty.

She is already 16years old. But she _______as if she were still a little girl.

In order to increase our output, we need to import more production _______.

The engineers in this lab spent several weeks _______their plans for the new bicycle.

We are _______ at the rapid progress Mark has made in this semester.

Much of the news provided by this newspaper is_______, not foreign.

Pine trees are usually believed to _______ cold weather.