不设专门的对照的研究是
A.病例对照研究B.队列研究C.个案调查D.分析性研究E.实验研究
参考答案:C
— I hear that Jason is planning to buy a car.
— I know. By next month, he ________ enough for a used one. [ ]
A. will have saved
B. will be saving
C. has saved
D. saves
消防通用安全绳内芯为高强度尼龙。