英文中形容詞有三個比較等級，因此，形容詞有原級的用法、比較級的用法和最高級的用法。

1. 形容詞的原級的用法主要是用于兩者之間程度是否相同的比較。

2. 肯定形式用as+原級形容詞+as+比較成分，表示“和...一樣”。

Tom is as tall as I (am).

湯姆和我一樣高。

And I am as fat as you (are).

而且我和你一樣胖。

The temperature is as high as (it was) yesterday.

今天的溫度和昨天一樣高。

3. as much/many...+ as... 表示前后數量相同。

I had just as many bones as you did.

我和你吃的骨頭一樣多。

4. 否定形式用 not so (as)+原級形容詞+as+比較成分，表示“不如...”。

Our hosts are not so nice as those of other dogs.

我們的主人不像其他狗的主人那樣好。

Jane is not so (as) tall as I (am).

珍不如我高。

We don’t look so strong as that guy.

我們看起來沒有那家伙壯。

5. as+形容詞原級+as+用作比喻的名詞，此結構形成了許多慣用語，多用于口語。

There! There! You are as hungry as a bear.

瞧！瞧！你餓得像只熊。

My God! It is as hard as a rock.

天啊！它硬得像塊巖石。