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