What a beautiful she is. = How beatiful this girl is. 这个女孩真漂亮 What fine weather. = How fine the weather is. 多好的天气 What a terrible journey. = How terrible the journey is. 多糟糕的一次旅行 What an interesting book. = How interesting the book is. 多有趣的一本书 What a good idea. = How good the idea is. 多好的主意
What a beautiful girl ! What beautiful girls ! What dirty water ! How time flies ! How fast he runs ! How beautiful the girl is ! How beautiful the girls are! How dirty the water is ! 认真分析以上句子的结构，你就会明白很多