评级系统必须有()个不同的评级维度。
A.2
B.3
C.4
D.5
参考答案:A
Harry Potter is a very nice film . I _____ it twice.[ ]
A. will see
B. have seen
C. saw
D. see
正常人尿渗量/血渗量为()
A.(3~4.5):1
B.>4.5:1
C.1:1
D.3:1
E.4:1