One piece of work of United Nations is to help poor in developing countries.A. / the

问题补充：

One piece of work of United Nations is to help poor in developing countries.

A. /, the, /

B. /, the, a

C. the, the, the

D. the, /, the

答案：

A. /, the, /

B. /, the, a

(答案→)C. the, the, the

D. the, /, the

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