These firemen are very helpful.(改为单数句子）

These firemen are very helpful.(改为单数句子） there firemen are very helpful 变单数句 these men doctors are very kind.改为单数句子 These are our sheep. （改为单数句子） These are old chairs(改为单数句子） These men are policemen.【改为单数句子】 These are my photos.改为单数句子 these are our apples改为单数句子 These are boxes. (改为单数句） These are oranges.(改为单数句） These are English students(改为单数） What are these?They are apples.(改为单数句子)That's a bus.(改为复数句子)