怀疑颅内肿瘤引起的头痛,首先应进行()
A.头颅B超
B.腰穿脑脊液检查
C.头颅MRI
D.脑电图
E.脑血流图
参考答案:C
If the traffic light is red, you _____ cross the road. It's dangerous. [ ]
A. don't
B. needn't
C. mustn't
D. wouldn't
下列物质的电子式书写正确的是
A.氯化铵 B .四氯化碳
C. 氮气 D. 二氧化碳