As high as 和 to a height of 是有分别的。to a height of 是中性的,只说明有多高。as high as 却有许多暗含的意义或是色彩。
例如:The flood water is as high as the roof of his house. 这是用来做比较的。这里不能用 to a height of 来代替。
It is amazing that he could have risen as high as he did when he does not know anything to speak of. 这是抽象的用法,也是不能用 to a height of 来代替的。
The tree has grown to a height of twenty feet in just two years. 这句如果说成 The tree has grown as high as twenty feet in just two years. 就有点不顺口,主要是因为应该用 tall 而不是用 high。
The airplane has flown to a height of 30,000 feet. 如果说:The airplane has flown as high as 30,000 feet. 就给人不完整的感觉。要消除这种感觉就要在后面加东西,如:The airplane has flown as high as 40,000 feet without encountering any problem. The airplane has flown as high as 40,000 feet before its engines became labored.
这些分别多看书就自然会学到。我也是从来没有想过这两个词组有什么分别,但是语感告诉我使用的方法。