什么是先进文化？
先进文化，是指以马克思主义为指导，以培养有理想、有道德、有文化、有纪律的四有公民为目标的面向现代化、面向世界、面向未来的，民族的科学的大众的社会健康积极向上的具有特色社会主义的文化。
修改病句
河水倒映在云朵里，显得更白了。
选择合适的句子，补全对话。（有两项是多余的）
A. What did you do yesterday?
B. Where did you go yesterday?
C. How many children were there at the party?
D. Yes, he did.
E. Why did you visit Mike?
F. No, they weren't.
G. How many children are there at the party?
A:Hello, Liu Yun. ____
B:I visited Mike.
A:____
B:Because it was his birthday yesterday.
A:Did he have a birthday party?
B:____
B:There were fifteen children at the party.
A:Were Mike's parents at home?
如图是表示气体分子的示意图，图中“○”和“●”分别表示两种不同的原子，其中表示单质的是____ ，表示化合物的是 ____ 。
