发生挫伤的原因是（）。
A、做了准备活动；
B、用力过猛；
C、活动方法正确；
D、做好了保护。
参考答案：B
箭头法
根据句意，用适当的介词或连词填空
1. Tom was watching TV____I was reading.
2. We do morning exercises every day____on rainy day.
3. You should be out ____staying at home on such a fine day.
4. We learn other subjects____English.
5. this way doesn't work, let's try another.
6. Could you help me take care_____these dogs?
