问题补充：
The teacher came into the classroom by his students.
A. following
B. to be following
C. followed
D. having followed.
答案：
A. following
B. to be following
(答案→)C. followed
D. having followed.
解析：考查非谓语动词。句意：老师进入教室被他的学生们跟着。The teacher与follow之间是被动关系，根据语境应用过去分词作伴随状语。所以选C。
