之前小編與大家一起學習了形容詞比較等級的構成方式，而形容詞比較等級用于句子當中便形成了所謂的“比較結構”。英語比較結構最主要的有三種：as...as結構，more...than結構以及the most...結構。as...as結構意為“和...一樣”，其用法主要如下：

一、基本模式：as+形容詞原級+as-分句

1.主句主語與as-分句主語不同，比較項目相同，此時as-分句有所省略。如：

Jack is as clever as Tom.

2.主句主語與as-分句主語相同，但比較項目不同，此時as-分句不可用省略句。如：

The girl is as brilliant as she is beautiful. (這個女孩既漂亮又聰明。)

3.主句主語與as-分句主語不同，比較項目也不同，此時as-分句不可用省略句。如：

Her uncle was as base and unworthy as her father had been upright and honorable.

(她叔叔卑鄙齷齪，不像她父親那樣正直可敬。)

4.基本模式的否定形式：

Jack is not as clever as Tom. 或 Jack is less clever than Tom.

二、變體模式：

1. as many/much+名詞+as-分句：

She has eaten as many apples as her sister.

He took as much water as he needed.

2. as+形容詞原級+名詞詞組+as-分句：

Lucy is as clever a girl as her sister.

3. 變體模式的否定形式：

He didn’t take as much water as he needed.

需要注意的是，同一句話，采取基本模式和變體模式，它們的含義基本相同，但句子的側重點有所不同。例如：

基本模式：I haven’t seen a car as old as this for years.(重點在名詞car)

變體模式：I haven’t seen as old a car as this for years.(重點在形容詞old)

三、as...as結構常用于形象比喻中：

as rich as a jew 極其富有 as cool as cucumber 沉著冷靜

as light as a feather 輕如鴻毛 as soft as butter 性格軟弱

as poor as a church mouse 一貧如洗 as clear as crystal 清澈透明，一清二楚

as busy as a bee 忙忙碌碌 as easy as ABC 相當容易

as deep as a well 高深莫測 as stubborn as a mule 非常頑固，倔脾氣