港口与航道工程施工总承包二级资质企业，具有二级资质以上项目经理不少于（）人。
A.10
B.15
C.20
D.25
参考答案：A
以下缩写中表示临界胶束浓度的是（）
A.HLB
B.GMP
C.CMC
D.MC
E.CMS-Na
To the parents' worry, some middle school students are ______ computer games and completely forget
their studies.[ ]
A. crazy about
B. very fond of
C. concerned for
D. serious about
