指出下列不是RC4切丝机刀辊传动组成（）.
A、左耳轴
B、进刀气缸
C、刀辊体组件
D、空气离合器
参考答案：D
The dam was not strong enough to _____ the flood waters. The people living there had to remove from their houses.[ ]
A. hold down
B. hold back
C. hold off
D. hold on
