现浇钢筋混凝土框架结构中竖向钢筋的连接，宜采用（）。
A.闪光对焊
B.电弧焊
C.电阻点焊
D.电渣压力焊
参考答案：D
They went to the hills and they _____ a good time there last week. [ ]
A. have
B. had
C. are having
D. have had
起动系使发动机由静止状态转入（）。
A.升温状态
B.运转状态
C.进气状态
D.压缩状态
