He taught in this school last year.(把last year改为 since last year)
He _________ _________ in this school _________ last year.
They didn't clean the classroom yesterday.（改为被动语态）
The classroom _________ _________ yesterday.
We have already returned the books.（改为否定句）
We _________ __________ the books ___________.
Rice is grown in China.（划线部分提问）
_________ is rice ___________?
