比较级（如 taller、more expensive）表示两样东西不一样。可如果它们一样呢？英语专门有一个结构来表达这个：as … as。
要记住的一条规则： 要说两样东西相等，把形容词或副词的原级夹在两个 as 中间：as + 形容词/副词原级 + as。不加 -er，也不用 more——只用原级。✅ as tall as，绝不是 ❌ as taller as。
表达相等：as … as
两样东西在某方面相等时，用 as + 形容词 + as：
- My brother is as tall as me.
- This café is as good as the one downtown.
- Her new phone is as fast as mine.
形容词保持原级——绝不用比较级。✅ as expensive as，绝不是 ❌ as more expensive as。
汉语常说“跟/和……一样 + 形容词”，如“这个跟那个一样贵”；英语则要说 as + 形容词原级 + as + 比较对象，如 as expensive as that one。注意不要按汉语顺序漏掉第一个 as。
这个结构不只用于形容词，也适用于副词：She finished as quickly as she could. · He didn't drive as carefully as usual.
本课只讲形容词和副词。数量的表达是另一种句型，本课不涉及：as much time as、as many books as。
否定形式：not as / so … as
要说两样东西不相等，在第一个 as 前加 not。也可以把第一个 as 换成 so——两种都对，但 not so … as 听起来更正式、更老派一些：
- This test wasn't as hard as the last one.
- He isn't as busy as he used to be.
- The film wasn't so exciting as I expected.（比 as … as 略正式）
注意这个否定形式的真正含义：not as hard as 只是说第一样东西没有第二样那么难，并没有说差距有多大。要表达差距的大小，需要下面的修饰语。
削弱或加强比较
可以在第一个 as 前加一个词，说明两样东西有多接近相等：
| 修饰语 | 含义 | 例句 |
|---|---|---|
| just as | 相等，带强调语气 | This one is just as good as that one. |
| nearly as / almost as | 非常接近，但稍逊一点 | She's almost as tall as her mother. |
| not quite as | 接近，但稍逊一点 | The sequel isn't quite as funny as the original. |
| not nearly as | 差得远——差距很大 | This café isn't nearly as cheap as the one near my home. |
- This laptop is just as fast as the old one — they feel equally fast.
- He isn't nearly as tired as he looks——这句强调差距很大。普通的 isn't as tired as 只是说他没那么累，并没有说差距有多大。
表示倍数差距：twice as、half as、three times as
要精确说明某样东西大或小多少倍，把倍数放在 as … as 前面：
- This flat is twice as expensive as my old one.（两倍）
- The queue moved half as fast as yesterday.（一半）
- Their new office is three times as big as the old one.（三倍）
在 B1 阶段，更清晰自然的说法是 倍数 + as + 形容词 + as：twice as big as。在更高级或专业的英语里，也会见到 three times bigger than 这样的说法，但可能显得含糊，所以本课坚持用更清楚的 as … as 结构。✅ twice as big as；在这个阶段，不建议用 ❌ twice bigger than。
as … as 与 -er / more 的区别
两种结构都用来比较两样东西，但回答的问题不同：
| 结构 | 回答的问题 | 例句 |
|---|---|---|
| -er / more + than | 谁在这一点上程度更高或更低？ | This one is bigger than that one. |
| as … as | 它们相等吗，或者有多接近相等？ | This one is as big as that one. |
-er / more 比较级前也可以加修饰语，来弱化或强化比较，并说明差距有多大（a bit bigger、much more expensive、far cheaper）——这是另一个话题，有它自己的一套修饰语，等 as … as 用熟了之后再学也不迟。
关于 as 后面代词的说明： 在日常口语中，宾格代词很自然：as tall as me、as good as her。在更正式的书面语里，也会见到主格代词加动词：as tall as I am、as good as she is。两种都对——宾格代词的说法只是听起来更随意一些。
常见错误
- ❌ She is as taller as me. → ✅ She is as tall as me.（用原级，不用比较级）
- ❌ This is as more expensive as that. → ✅ This is as expensive as that.
- ❌ It's twice bigger than the old one. → ✅ It's twice as big as the old one.（这个层次，倍数要和 as … as 搭配）
- ❌ He isn't so good than her. → ✅ He isn't as good as her / ✅ He isn't so good as her.（as … as / so … as，绝不是 so … than）
- ❌ This bag is not as cheap than that one. → ✅ This bag is not as cheap as that one.
小测验
用正确的形式补全每个句子：
- My sister is ____ (tall) ____ me.（两人身高完全一样）
- This coffee isn't ____ (strong) ____ the one at home.（这杯更淡）
- The new bridge is ____ (long) ____ the old one.（正好两倍长）
- He's ____ (fast) ____ his brother — just a tiny bit slower.（用 almost）
- This flat is ____ (big) ____ my last one — a huge difference.（用 not nearly）
显示答案
- as tall as 2. as strong as 3. twice as long as 4. almost as fast as 5. not nearly as big as
要点回顾
- 表达相等用 as + 形容词/副词原级 + as——绝不用比较级：✅ as tall as，绝不是 ❌ as taller as。
- 否定形式是 not as / so … as：not as hard as、not so exciting as。
- 用 just as（相等）、nearly / almost as（非常接近）、not quite as（稍逊一点）、not nearly as（差距很大）来削弱或加强语气。
- 用倍数表示精确差距：twice as、half as、three times as——比把倍数放在 -er / more 前面更清楚。
- as … as 问的是“它们相等吗？”；-er / more + than 问的是“谁的程度更高？”——问题不同，结构也不同。