这个句子是错误的.正确的应该是以下几种说法：
How exciting this weekend was!
What an exciting weekend it was!
How exciting a weekend it was!
So exciting was this weekend !
下面把英语感叹句的有关情况做一简单介绍,希望对你有所帮助.
感叹句通常有what,how引导,表示赞美、惊叹、喜 悦、等感情.
what修饰名词,how 修饰形容词,副词或动词,感叹句结构主要有以下几种：掌握它的搭配,即掌握了感叹句的重点.
How +形容词+ a +名词+ 陈述语序
How+形容词或副词+ 陈述语序
What +名词+ 陈述语序
What+a+形容词+名词+ 陈述语序
What+ 形容词+复数名词+ 陈述语序
What+ 形容词+不可数名词+ 陈述语序
How clever a boy he is!
How lovely the baby is!
What noise they are making!
What a clever boy he is!
What wonderful ideas (we have)!
What cold weather it is!
感叹句的省略形式为：
What a clever boy (he is)!
典型例题
1）___ food you've cooked!
A.How a nice B.What a nice C.How nice D.What nice
答案D.由于How 修饰形容词,副词；what修饰名词.且food为不可数名词,因此A,B 排除.C How + adj.后面不能再加名词,因此只有D正确,其句型为What + adj.+n.(不可数)
2）___terrible weather we've been having these days!
A.What B.What a C.How D.How a
答案A.weather为不可数名词,B,D排除.C为how + adj.后面不应有名词.只有A,符合句 型What +形容词+不可数名词.
3) --- _____ I had!
--- You really suffered a lot.
A.What a time B.What time C.How a time D.how time
答案A. 感叹句分两类：1：What + n.+主谓部分
2：How + adj./ adv./ v.+主谓部分.本题属第一种,但省略了bad,相对于 What a bad time I had!这是个习惯用语.