国家对危险化学品经营销售实行制度。()
A.许可
B.登记
C.审批
参考答案:A
医学伦理学作为一门独立的学科首先产生于()
A.英国
B.法国
C.意大利
D.美国
E.中国
The meeting () in October, but the plan has been put off again and again.
A. was to have been held
B. ought to have held
C. was to be held
D. must have been held