急性出血量多少时应立即输血
A.200~400ml
B.400~600ml
C.600~800ml
D.800~1000ml
E.>1000ml
参考答案:E
We _______ clean our classroom, because it's too dirty. [ ]
A. may
B. can
C. must
D. needs
()放大了金融衍生工具的风险。
A.衍生性
B.可复制性
C.杠杆效应
D.提高交易效率