只允许介质向一个方向流动，阻止反方向逆流的阀门是（），常用的类型有（）和（）。
参考答案：止回阀；旋启式止回阀；升降式止回阀
The teacher asked us to ______ in our cxercise books.[ ]
A. write up it
B. write it up
C. write down it
D. write it down
根据中文意思完成句子。
1. 别在阳光下看书，这对你的眼睛有害。
Don't read in the sun. It ________ your eyes.
2. 你愿和我一起去打篮球吗？
________ go and play basketball with me?
3. 今天太晚了，你最好明天来。
Ws too late. ________ come here tomorrow.
4. 昨天玛丽花了一小时做家务。
Mary ________ housework yesterday.
5. 让杰克每天晚上复习功课两个小时恐怕很困难。
________ Jack go over his lessons for two hours every evening.
