I hope they will finish the project in time but they themselves are very that it will.A.

问题补充：

I hope they will finish the project in time, but they themselves are very that it will.

A. certain

B. confident

C. doubtful

D. suspicious

答案：

A. certain

B. confident

(答案→)C. doubtful

D. suspicious

解析：doubtful doubtful about/of/that...“对……疑惑的，不肯定的”；

be confident“有信心的”；be certain of/about/ that“对……确定的”; be suspicious of/that“对有怀疑，有疑心的”