预应力钢绞线成批验收，每批重量不大于（）。
A.50t
B.60t
C.70t
D.100t
参考答案：B
When the fire broke out, Mary didn't know _____. [ ]
A. what do
B. what thing to do
C. what to do
D. to do what
YZ为（）电动机。
