托辊在皮带机中的作用？
参考答案：
（1）支撑运输带与物料。
（2）防止和纠正输送带跑偏。
（3）缓和物料对输送带的冲击。
根据图片提示，照样子写五句话样子写五句话。
例: I can see a rainbow.
1. ____________________________________________
2. ____________________________________________
3. ____________________________________________
4. ____________________________________________
5. ____________________________________________
The fireman succeeded in saving all the people in the house on fire, _______they knew they were in great danger themselves.
A．because
B．since
C．unless
D．though
