what（）lovely weather it is A,/
用what引导的感叹句有三种句式，此时，what为形容词，用作定语，修饰它后面的名词或名词词组。
1. What+a/an+形容词+可数名词单数+主语+谓语!例如:
What a nice day it is!多么好的天气啊!
What an interesting book that is!那是一本多么有趣的书啊!
2. What+形容词+可数名词复数形式+主语+谓语!例如:
What beautiful flowers they are!多么美丽的花啊!
What good teachers they are!他们是多么好的老师啊!
3. What+形容词+不可数名词+主语+谓语!例如:
What fine weather it is!多好的天气!