在汽车式起重机行驶转向系统中,()转向器的传动副的主动件为转向蜗杆,从动件为装在摇臂轴曲柄端部的指销。
A.全液压式
B.蜗杆曲柄指销式
C.齿轮齿条式
D.循环球式
参考答案:B
胎儿和母体交换物质的器官是[ ]
A.脐带
B.羊水
C.胎盘
D.子宫
I have got a lot of CDs of the most popular singers. I can't decide _____. [ ]
A. which one to listen to
B. to listen to which one
C. which one should I listen to
D. what I should listen to