15．We know it is hard to make such a decisionhe has just built up the team for a year and

问题补充：

15．We know it is hard to make such a decisionhe has just built up the team for a year and the project is going through the important stage now.

A. that

B. as

C. when

D. Before

答案：

A. that

(答案→)B. as

C. when

D. Before

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