enough
enough to do和doing不能进行比较，因为enough后面不能加doing，enough后面一般只加不定式,构成固定搭配：...enough + 名词 + （for sb） to do sth 或 ...形容词/副词 + enough (for sb) to do sth。
enough的用法
一、enough可以作名词、代词，意思是"足够;充分"。作代词可以代替可数名词或不可数名词，在句中作主语或宾语。
例句：
Enough has been said on this subject.
关于这一问题说得已经足够多的了。
注意：当enough后的名词前有冠词、形容词性物主代词、指示代词或其本身就是代词时，要用介词of。
例句：
We've had enough of your coldness.
我们已经受够了你的冷漠。
二、enough作形容词，意思是"足够的;充分的"，常与for或不定式连用，可以作定语或表语。作定语置于被修饰的名词前后均可，前置时强调enough，后置时强调被修饰词。
例句：
Five men will be quite enough.
五个人就足够了。
三、enough作副词的意思是 "十分地;充分地;足够地;充足地"，置于被修饰的形容词或副词之后，常与不定式或介词for连用 ，在句子中作状语，表示程度。
例句：
When they reached the burning building they found that their ladders were not long enough to reach the people who were trapped.
当他们靠近烈火熊熊的大楼时，他们发现梯子不够长，够不着那些被火围困的人。
四、enough作感叹词时意思是"够了;停止;住手;不要再继续了"，用以表达不耐烦或恼怒。
例句：
You've been practising the violin all afternoon. Enough!
你整个下午都在练小提琴。够了!
五、用在"主语+cannot...+enough"句型中该句型形式上是否定句型，实际上表达的是肯定意义，意思是"再……也不过分;越……越……"。
例句：
I cannot thank you enough.
我对你感激不尽。(我怎么感谢你都不算过分。)
enough的短语
1.Three hundred million dollars will be nothing like enough.
3亿美元远远不够。
2.The plan is good; the problem is it doesn't go far enough.
计划不错;问题在于不够深入。
3.America has enough firepower in the area to mount sustained air strikes.
美国在该地区拥有足够的火力发动持续的空中打击。
4.McGregor's effort was enough to edge Johnson out of the top spot.
麦格雷戈奋力一搏，成功地将约翰逊从第一的位置上挤了下来。
5.I met him only the once, and that was enough.
我就见过他那一次，那就让我受够了。
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