港口与航道工程施工总承包一级资质企业，一级资质项目经理应不少于（）人。
A.10
B.15
C.20
D.30
参考答案：B
表层肠黏膜坏死脱落后形成
A．糜烂
B．溃疡
C．包裹
D．瘘管
Without water it ______ impossible to live on the earth.
[ ]
A. is
B. would
C. were
D. would be
