Milk,cheese,butter and yogurt contain calcium,---------?变反意疑问句,
问题描述：
Milk,cheese,butter and yogurt contain calcium,---------?变反意疑问句,
答
don't they?
答
Milk,cheese,butter and yogurt contain calcum,don't they?
and which food do you prefer?i'd like yogurt,because i never try it before.