— How many ____________ are there?
— There are four.[ ]
A. butterfly
B. butterflies
答案:B
凡是能发生事故的潜在因素叫()
A、毒素
B、危险物
C、隐患
D、以上均错误
热病治疗大法为()
A.祛风
B.散寒
C.祛湿
D.清火
E.通其脏脉