He never does his work _____ Mary. [ ]

A. as careful as

B. so careful as

C. as carefully as

D. carefully as

下列错误的提法是（）。

A.总时差最小的工作是关键工作

B.关键线路上不能有虚工作

C.关键线路上工作的总持续时间为最长

D.关键线路上的工作都是关键工作