问题补充：
【小题1】He taught in this school last year.(把last year改为 since last year)
He has taught,since wasn’t cleaned in this school haven’t returned,yet last year.
【小题2】They didn’t clean the classroom yesterday.（改为被动语态）
The classroom Where grown yesterday.
【小题3】We have already returned the books.（改为否定句）
We the books .
【小题4】Rice is grown in China.（划线部分提问）
is rice ?
答案：
解析：
【小题1】把last year改为 since last year，时间由时点变为时段，那么时态也就相应的由一般过去式变为现在完成式。
【小题2】被动语态的结构是 Be+动词过去分词，而且句式是一般过去式。
【小题3】现在完成式的否定结构是has(have)后面加not, already与肯定句式连用，yet与否定句式连用。
【小题4】对地点的提问用疑问副词where。
