机泵预冷正确的方法是（）。
A.快速冷却
B.慢速均匀预冷
C.边冷却边盘车
D.预冷期间不允许盘车
参考答案：B, C
根据句意和首字母填空。
1. Li Lei won first p________ in the speech competition.
2. At the college, he m________ in English.
3. Tiger Woods started g________ when he was only ten months old.
4. It is u________ for this girl to know so much about math.
5. The old woman t________ the USA and she had a good trip.
6. She held the world r________ for sneezing.
观察如图，根据血流方向，判断②是（ ）
A．动脉
B．静脉
C．毛细血管
D．肾小管
