----Are you sure that he is able to do the work well? ---- he could give his mind to it.

问题补充：

----Are you sure that he is able to do the work well?

---- he could give his mind to it.

A. In case

B. If only

C. On condition that

D. Unless

答案：

A. In case

(答案→)B. If only

C. On condition that

D. Unless

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