原始开工前，对给电子体管线要作的工作有（）.
A、液压强度试验
B、气密
C、氮气吹扫
D、油运
参考答案：A, B, C, D
听朋友打来的电话，往往凭声音就知道是谁．这是为什么？
This lifeboat is for women and children only. You _____ wait. [ ]
A. should
B. need
C. can
D. would
