为什么要用as hot a day as

题目

为什么要用as hot a day as
有个改错题是It was as a hot day as the day before yesterday.答案告诉的是a hot变成hot a ,

答案

“as + 形容词或副词原级 + as…” 结构的变体形式是“ as + 形容词 + a + 单数名词 + as 或 as + many/much + 名词 + as ”.意为“……和……一样…… " .例如：
I don't want as expensive a car as this.＝ I don't want a car as expensive as this ．
我不要这么贵的汽车.
This is as good an example as the other is.
这个例子和另外一个例子一样好.
Tony is as clever a boy as his brother ．