是将药物通过水洗或漂去杂质，达到洁净目的（）
A.挑选
B.筛除
C.筛选
D.风选
E.水选
参考答案：E
28. Li Ping is the only one of the students whom I think _______ fit for the job.
A．being
B．is
C．to be
D．be
耐受性定律
