How different life today is from what was fifty years ago 这句中为什么开头用how 而不用what

问题描述:

How different life today is from what was fifty years ago 这句中为什么开头用how 而不用what

改成what a的话,句子要变成
What a different life it is today from what was fifty years ago.
How + adj/ adv + 主语+ 谓语
What + a/an+ adj +n + 主语和谓语
改成what a 原句要重新加主语了!