A very exciting thing happened this evening after dinner．I was outside my apartment with my friend Sunny and suddenly some funny clowns came dance down the street．After they had been gone，a beautiful lady rided past on a wonderful white horse．She told us that there had a circus in town tomorrow night．Then a man came along with two tiny dog．One of the dogs had a plastic envelope in it mouth．The man told us to take the envelope．When we open it，it had two free tickets of the circus inside．We were so surprising．Tomorrow is going to be best night ever!
A very exciting thing happened this evening after dinner．I was outside my apartment with my friend Sunny and suddenly some funny clowns came dance down the street．After they had been gone，a beautiful lady rided past on a wonderful white horse．She told us that there had a circus in town tomorrow night．Then a man came along with two tiny dog．One of the dogs had a plastic envelope in it mouth．The man told us to take the envelope．When we open it，it had two free tickets of the circus inside．We were so surprising．Tomorrow is going to be∧best night ever!
详解：
1．dance改为dancing；考查分词作状语，clowns 与动词dance存在逻辑上的主谓关系，故用现在分词形式作状语．
2．去掉been；考查动词的语态，分析句意为"他们走了之后"，这里主语和动词是主动关系，故去掉been．
3．rided改为rode；考查动词的不定式，ride过去式为不规则变化rode．
4．had改为was；考查固定句型，分析句意为"这里有一场马戏表演"，这是一个存现句，要用there be句型，be 的单复数形式与后面的名词的单复数形式保持一致；动词have也可以表示"有"，但英语中没有there have这种表达方法，故把had改为was．
5．dog改为dogs；考查名词复数，dog是可数名词，前面有数词two，故用复数形式dogs．
6．it改为its；考查物主代词，分析句意为"其中一只狗的嘴里叼着一个塑料信封"，所以要用形容词性物主代词its作mouth的定语，意为"狗的嘴里"．
7．open改为opened；考查动词的时态，这里讲的是发生过的事情，故用一般过去时opened．
8．of 改为to；考查介词，ticket后面用to/for，这是固定用法，不能用of．
9．surprising改为surprised；考查分词作形容词，现在分词作形容词修饰物，过去分词作形容词修饰人，故此处应该用过去分词surprised作形容词．
10．best前面加the；考查定冠词，形容词或副词的最高级前面要加定冠词the．