高频保护是比较线路两端电压大小的一种保护装置。()
参考答案:错
We were very busy yesterday. Otherwise we _____part in the discussion.
A.would take
B.did take
C.had taken
D.would have taken
先兆流产与难免流产的主要鉴别要点是:()
A.出血时间长短
B.下腹痛的程度
C.宫口扩张与否
D.早孕反应是否存在
E.妊娠试验是否阳性