小芳买了10张光盘,每张光盘15元.小红买了2个鼠标,每个鼠标70元.小芳比小红多付多少钱?
10×15-2×70
=150-140
=10(元)
答:小芳比小红多付10元.
.He suddenly saw what looked like a snake in the darkness. For an instant his heart seemed to stop ______.
A.to beat
B.beating
C.beaten
D.being beaten
什么是杂多阴离子和杂多酸?