what are they?they are apples改为单数句

what are they?they are apples改为单数句 把They are apples.改为单数句 they are apples改为单数 What colour are they?改为单数句 are they apples?改为单数形式 What are these?They are apples.(改为单数句子)That's a bus.(改为复数句子) they are orange sweaters 改为单数句 They are American teachers(改为单数句) Are they women doctors? 改为单数句 They are my friends.改为单数句 They are old jeeps. (改为单数句) Are they students?（改为单数句）