It is no longer a problem the poor children in this district can go to school.A. thatB. w

问题补充：

It is no longer a problem the poor children in this district can go to school.

A. that

B. whether

C. so

D. because

答案：

A. that

B. whether

C. so

D. because

解析：句中it是形式主语，代替 that引导的主语从句。