带式输送机的牵引力调整
参考答案：
（1）在滚筒上包上皮革或橡胶以增加摩擦力
（2）改变带的环绕方式以增大包角
It even leaves the scientists in wonder _____ they should call the newly-born creature, which looks
half-human and half-animal.[ ]
A. that
B. why
C. what
D. how
发动机进行暖机动行，低速旋转大约（）分钟。
A、3
B、5
C、8
D、10
