下列元素中，属于非金属元素的是[ ]
A．钾
B．钙
C．碳
D．汞
答案：C
系统中已设置白银大额优惠，购买1千克以上（）元/克。
__________ gone is gone.__________ no use talking about it any more. [ ]
A. That's; It's
B. What's; It's
C. It's ; That's
D. That's ; That's
