the teacher entering the classroom the boy pretended the text.A. To see ; to readB. Seen

问题补充：

the teacher entering the classroom, the boy pretended the text.

A. To see ; to read

B. Seen; reading

C. Seeing; to be reading

D. Seeing; to have read

答案：

A. To see ; to read

B. Seen; reading

(答案→)C. Seeing; to be reading

D. Seeing; to have read

解析：see和其逻辑主语之间是主动关系，故用现在分词作时间状语；pretend后可跟不定式的三种形式：to do (一般式)，to be doing(进行式)，to have done（完成式），分别表示现在、进行和完成的动作，这里表示进行，故用to be reading。