as...as本身就有与什么相同之意,...部分是形容词,比如
Tim is as tall as Jane,Tim 和 Jane 一样高。
Tim is as hard-working as Jane,Tim 和 Jane 一样勤奋。
similar本意是相似的,如This egg is similar to that one.这个鸡蛋和那个鸡蛋很像。
as simiar as也有这种表达,但是很少出现。其实意思上等同于 be similar to,但是在英语的一个句子中动词只能出现一个,所以就有了as similar as这样的短语来替换 be similar to了。举个例子
I buy an egg as similar as that one at home.我买了个和家里一样的鸡蛋。
I buy an egg that is similar to that one at home.意思跟1 一样
所以发现没,其实主要是因为语法问题,句子1里面,因为buy 已经是动词,一个句子里面不能再出现动词(be 也是动词),所以就用了as similar as,2中之所以用了is (be变形),是因为套用了定语从句,不知道我说明白了没,嗯,大概就是这样!
(另外similar常用搭配是sb is similar with sth 某人对某物比较熟悉 / sth is similar to sb 某物为某人所熟悉,比如He is similar with Xiamen.或Xiamen is similar to him.都是他对厦门很熟悉)