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
参考答案：A
He failed the mid-term examination and only then _____ how much time he had wasted. [ ]
A. he realized
B. did he realize
C. he had realized
D. had he realized
现有产品每（）年进行一次后评估。
A.半年
B.一年
C.一年半
D.两年
