消防车每（）小时必须对蓄电池的容量及液面高度进行检查。
A.20.0
B.30.0
C.50.0
D.60.0
参考答案：C
Before the first nonstop flight made in 1949, it_____ necessary for all planes to land for refueling.
A．would be
B．has been
C．had been
D．would have been
急性腹痛在诊断不明确的情况下，不可应用（）
A.吗啡
B.阿托品
C.苯巴比妥
D.胃肠减压
E.腹腔试穿
