The teachers always plain about the children in class.
A. to teach, tired
B. teaching, tired
C. teaching, tiring
D. to teach, tiring
网友回答
A. to teach, tired
(答案→)B. teaching, tired
C. teaching, tiring
D. to teach, tiring
解析：plain about doing sth是固定搭配；劳累的孩子应用tired来修饰。