how引导名词性从句有如下几种情况：

(1）表方式、方法，相当于the way in which。可译作“怎样、怎么”。

I didn't know how he came here.

(2)表程度上的感叹，可译作“多么……、真……、这么……”等。

He said how beautiful those flowers were.

He said how he regretted the hours wasted in the woods and fields.

He was surprised at how much water I had drunk.

(3)表对程度、数量、情况的疑问。

She wondered how he loved her.

I don't know how many students there are in our school.

I have no idea how my mother is now.

I want to know how he is getting on with his studies.

(4)用作连词，相当于the fact / situation / times... that, 可译作“……的样子”、“……的情形”、“……的情景” 、“……的经历”等。

I still remember how they laughed.

I still remember how I left my hometown for the first time.

I won't forget how we lived together.

I won't forget how I lived in my childhood.

这个句子中how+形容词引导的都是名词性从句，作know的宾语。how为疑问副词表示程度。不是引导感叹句的how。例如：

How big is his room?

I don't know how big his room is.

I know how big his room is.

以上三句中的how都翻译为“多么”或“多”，不能因为汉译为“多么”就认为是感叹句。第三句主句为肯定句，谓语为知道，汉译为“我知道他的房间有多么大。”表面看好像how没有疑问含义，其实这句话中的how和特殊问句中how的意义是一样的，都是“大小程度如何”的意思，也就是说这里how仍表示疑问含义。

感叹句的交际功能是表示说话人情不自禁地的感情外露发出赞叹。在从句中多与主句的surprise、strange，unbelievable, exclaim等表达惊讶、惊叹、不可思议、难以置信等意义的词语呼应。动词know之后表示主语知道或不知道某种情况，这种语境是不可能用感叹句作宾语的。