病例对照研究中，病例的选择最好是( )。
A．新发病例
B．死亡病例
C．现患病例
D．现患病例和死亡病例
E．新病例与死亡病例
参考答案：A
— Must I finish my homework now?
— No, you _____.
A. mustn’t B. needn’t C. can’t
the deadline approaching, we found ourselves a loss about what to do.
A．With; at
B．As; about
C．As; for
D．With; by
