—Can those at the back of the classroom hear me?　　　　—No problemA. seatB. sitC. seatedD.

问题补充：

—Can those at the back of the classroom hear me?

—No problem．

A. seat

B. sit

C. seated

D. sat

答案：

A. seat

B. sit

C. seated

D. sat

解析：seated at the back of the classroom为后置定语，修饰those。