升降横移类停车设备的横移传动机构由（）组成。
A.电机减速机；
B.驱动轮；
C.从动轮；
D.地面铺设的导轨。
参考答案：A, B, C, D
They asked _____ to improve the soil. [ ]
A. that it was hard
B. whether it was hard
C. if it is hard
D. when was it hard
人体发育的起点是
A．婴儿
B．胎儿
C．卵细胞
D．受精卵
