— John could you please the black-board now? It’s your duty today.— OK. I’ll do it right

问题补充：

— John, could you please the black-board now? It’s your duty today.

— OK. I’ll do it right away.

A. not to clean

B. to clean

C. not clean

D. clean

答案：

A. not to clean

B. to clean

C. not clean

(答案→)D. clean

解析：句意：约翰，现在能请你把黑板擦了吗？今天该你值日。——好吧，我立即做。句式could you please后面接动词原形，表示客气的请某人做某事，故选Ｄ。