A:铜离子﹣Cu+2
B:两个氢分子﹣2H
C:熟石灰﹣Ca(OH)2
D:氧化铁﹣FeO
____ are in the ____ grade.
It is on Sunday.My friends and I will go to the bookshop.I like reading____.It is interesting.Sue likes reading____books.Sam doesn't like reading books.He wants to buy a ____.So his subjects are very good.My grandparents like reading____every day.But my parents like reading____.They often read them in the evening.