Question

4. Then the professor walked onto the platform and seated himself in a chair,   for answering questions.

A. had prepared     B.  being prepared

C. preparing        D. prepared

Answer 1

4.    D考查非谓语动词。句意：然后教授走上讲台，坐在椅子上，准备回答问题。此处be prepared for sth意为"准备好了做某事"，过去分词短语作伴随状语。所以选D。