請教as.... as的問題?

你所舉的例子是基本型式，as + adj + as
You are as tall as I. (第二個as 是 prep.)
The thing went as straight as I thought. (第二個 as 是 conjunction)

Alcohol is harmful, just as smoking is.
可以寫成
Alcohol is as harmful as smoking.
這句話畢竟簡單了一些，如果我想在 harmful 後強調對健康有害 to your health.
Alcohol, like smoking, is harmful to your health.
可以如此表達
Alcohol is as harmful to your health as smoking.
= Alcohol is as harmful as smoking to your health.
(介系詞片語 to your health 用來修飾 harmful)

字詞稍作修改，是不是就如你的原句
Alcohol can be as destructive to a PERSON'S health as smoking.

prep.+adj.+conj.
=as+adj.+as
=as (--) as
as straight as
as tall as
as destructive (to somebody's health,adj.phr.)as;is=can be;
as destructive as(smoking to somebody's health;gerund,a verbal noun, co-ordinate phr, equal in rank to,joined by a conjunction to;to co-ordinate ideas;)
as far as ---far
as long as ---on condition that--You can go to the party where you like as long as you get back before 12 midnight.
as good as---the same thing as---Will you be as good as your words ?--Will you do what you promised ?--You are as good as God, almost God, sure to be praised=praised be to God.