[典例剖析] 单项选择。
() — the workers repairing machines in the workshop(车间)?
—. They lunch in the canteen.

A.Do；No；have
B.Are；No；are having
C.Be；Yes；do having
点拨 根据问句中的 repairing 可知，问句为现在进行时的一般疑问句，且主语 the workers 为第三人称复数，句首的 be 动词要用 Are；答句的第二句表述的正在做的事情与问句问的不一致，由此可知，此句为否定回答的补充说明。故选 B。

B

[反馈练习] 按要求完成下列各题。
1. Peter and I are peeling the potatoes in the kitchen.(改为一般疑问句)
Peter and the potatoes in the kitchen?
2. —你正在看电影吗? —不。我正在看书。(根据中文提示完成对话)
— a film?
—No. a book.
3. — in the living room?(child，do puzzles)
—Yes，they are.(根据提示补全问句)

1. Are，you peeling 2. Are you seeing/watching，I'm reading 3. Are the children doing puzzles