HXD3型电力机车网压低于17.5kV时，低压保护环节动作，网压高于（）kV时过压保护环节动作。
参考答案：31.5
一 Why didn't you remind him of the possible danger?
一 But what _____ otherwise? He never listens to me. [ ]
A. could I do
B. could I have done
C. should I do
D. must I have done
《行路难》（金樽清酒斗十千）是李白什么时候所写（）
A、刚到长安时所写
B、在长安期间所写
C、离开长安时所写
D、离开长安后所写
