-----Is that your book ?----No .A. they areB. they aren’tC. it isD. it isn’t.

问题补充：

-----Is that your book ? ------No, .

A. they are

B. they aren’t

C. it is

D. it isn’t.

答案：

A. they are

B. they aren’t

C. it is

(答案→)D. it isn’t.

解析：句意：---那是你的书吗？----不，不是。否定答语中，no后应用否定形式；yes后市肯定形式。前句用that，答语应用it。故选D。