The professor along with his assistant came in by a group of excited students. A. follow

问题补充：

The professor along with his assistant came in, by a group of excited students.

A. follow

B. following

C. followed

D. to follow

答案：

A. follow

B. following

(答案→)C. followed

D. to follow

解析：followed为过去分词，表被动。