1、they are from the u.s.a.【改为一般疑问句,并作肯定回答】【 】 【 】from the u.s.a.yes,【 】 【 】2、 this is a book.【 改为一般疑问句,并作否定回答】 【】【】a book?no,【】【】.

1、they are from the u.s.a.【改为一般疑问句,并作肯定回答】【 】 【 】from the u.s.a.yes,【 】 【 】2、 this is a book.【 改为一般疑问句,并作否定回答】 【】【】a book?no,【】【】.
1、they are from the u.s.a.【改为一般疑问句,并作肯定回答】
【 】 【 】from the u.s.a.yes,【 】 【 】
2、 this is a book.【 改为一般疑问句,并作否定回答】 【】【】a book?no,【】【】.

1、they are from the u.s.a.【改为一般疑问句,并作肯定回答】【 】 【 】from the u.s.a.yes,【 】 【 】2、 this is a book.【 改为一般疑问句,并作否定回答】 【】【】a book?no,【】【】.
are they from the u.s.a.yes,they are.
is this a book?no,it isn't

Are they they are
is this it isn‘t