结核性胸膜炎,首次抽取胸液一般不超过()
A.1000ml
B.2000ml
C.700ml
D.800ml
E.500ml
参考答案:C
If someone falls off the ladder and gets seriously hurt, you’d better leave him _____ he falls and try to get help.
A.before
B.when
C.where
D.what
师生关系在社会道德上是一种______的关系。