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
网友回答
A. had prepared
B. being prepared
C. preparing
D. prepared
解析：
本题主要考查对句子结构的理解。根据句子中的walked onto…and seated himself…可知，句子表示几个动作的延续，应该用几个动词的并列答案选D。