问题补充：
---Do the people in Australia speak French?
--- .
A. Yes, they are.
B. No, they aren’t.
C. Yes, they do.
D. No, they don’t.
答案：
A. Yes, they are.
B. No, they aren’t.
(答案→)C. Yes, they do.
D. No, they don’t.
解析：英语一般疑问句的回答,一般要保持与上文人称,时态和数的一致,根据上文,可知选C.
