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

—Your grandparents were very great.                            —Yes. They supported my father’s schooling ______ they were very poor.

I really enjoyed your speech, ______ there were some parts I didn’t quite understand. 

Tom got all A’s ________ he spent most of his time studying.

 —How do you like the popular documentary “A Bite of China”（《舌尖上的中国》）?—Excellent! You won’t realize how wonderful our Chinese food is _____ you watch it.