病例对照研究与队列研究的主要相同点是
A．均是分析性研究
B．均是前瞻性研究
C．均是回顾性研究
D．均是实验性研究
E．均是描述性研究
参考答案：A
— I left my handbag on the train, but luckily someone gave it to a railway official.
— How unbelievable to get it back! I mean, someone ________ it. [ ]
A. will have stolen
B. might have stolen
C. should have stolen
D. must have stolen
A．5A
B．5A
C．3.5A
D．3.5A
