WTRZ—2000型钻机采用空气震击钻井时，钻杆螺纹部分须用（）润滑。
A、油脂
B、机油
C、铅油
D、以上均可以
参考答案：C
When she heard that she had been admitted by Qinghua University, she jumped with ________. [ ]
A. thrill
B. fright
C. surprise
D. terror
要清楚地表示各种数量的多少，用______统计图表示比较合适．
