Learning to write is learning to think. You don’t know things clearly _________ you can writethem down.

Animals are part of nature. _____ should be well prepared.

The rivers will become dirtier and dirtier _______ we take action to protect them.

It’s _______ hot _______ cold all the year round in Kunming. It’s called “Spring City.”

Hurry up, Jack. We have to get to the station before 11:45         we can catch the 12:00 train.