When to our school the new study methods are popular with all the students.A. to introd

问题补充：

When to our school, the new study methods are popular with all the students.

A. to introduce

B. introduced

C. introducing

D. to be introduced

答案：

A. to introduce

(答案→)B. introduced

C. introducing

D. to be introduced

解析：非谓语动词,过去分词表被动。