They often helped each other when they were at school.把这句话改成否定句和疑问句.急
问题描述：
They often helped each other when they were at school.把这句话改成否定句和疑问句.
急
答
they didn't often help each other when they were at school
did they often help each other when they were at school?
答
他们以前在学校经常互相帮助
答
They didn't often help each other when they were at school.
Did they help each other when they were at school?