一项队列研究中,暴露因素的RR值的95%的可信区间为0.5~2.1,那么该因素可能是
A.危险因素
B.保护因素
C.混杂因素
D.无关因素
E.有害因素
参考答案:D
--- The free gift doesn’t look good. --- _____, madam, but if you want good quality, you have to
pay for it. [ ]
A. No doubt
B. No offence
C. No problem
D. No way
某年的6月有5个双休日,你知道这年的6月1日是星期几吗?