英语中有几个意思相近的单词，它们都可以意为”害怕的“，包括 afraid，scared 和 frightened 等；它们经常被混用，但是你会发现你用着用着就总感觉哪里会出错，事实也是它们还是有一定的区别的。
Afraid，scared 和 frightened 经常被认为是同一个东西，它们的最大共同点就是，它们都可以跟在名词后面，例如：
小狗们害怕猫。
The puppies are afraid of the cat. (正确)
The puppies are scared of the cat. (正确)
The puppies are frightened of the cat. (正确)
我开始害怕夜间单独外出了。
I started to feel afraid of going out alone at night. (正确)
I started to feel scared of going out alone at night. (正确)
I started to feel frightened of going out alone at night. (正确)
然而，它们还是有比较大的区别的，我们可以从以下几个方面来分析它们的区别，例如：
一、能否作前置定语
Afraid 不能作前置定语，而 scared 和 frightened 可以，这是它们最主要的区别之一，例如：
受惊的猫从狗身边跑开了。
The scared cats ran away from the dog. (正确)
The frightened cats ran away from the dog. (正确)
The afraid cats ran away from the dog. (错误)
二、能否接动词不定式
Afraid 和 scared 后面常接动词不定式，而 frightened 不常用，例如：
她不敢开门。
She was afraid to open the door. (常用)
She was scared to open the door. (常用)
She was frightened to open the door. (不常用)
她不敢告诉他到底发生了什么。
She's afraid to tell him what really happened. (常用)
She's scared to tell him what really happened. (常用)
She's frightened to tell him what really happened. (不常用)
三、连接的介词
Scared 和 frightened 后面常接介词 by 或 of，而 afraid 后面只接 of，不能接 by，例如：
你怕蜘蛛吗？
Are you afraid of spiders? (正确)
Are you afraid by spiders? (错误)
当这些词与 of 连用时，通常表示一直经历的一种心理状态，例如：
She is scared of alone.
她不敢一个人外出。
I'm frightened of walking home alone in the dark.
我害怕在黑夜单独走路回家。
而当与 by 连用时，通常表示产生结果的某个突发事件，例如：
He was scared by the thunder.
他被雷声吓了一跳。
Most are frightened by the sight of blood.
大多数孩子见到血就害怕。
四、是否是分词形容词
Afraid 之所以不同的另外一个原因是，它不是分词形容词，而 scared 和 frightened，类似的还有 terrified，horrified，petrified 和 spooked 等是分词形容词，它们都是对应动词的过去分词，也就是我们常说的以 -ed 结尾的。
1. 通常过去分词（以 -ed 结尾）用来谈论某人的感受，例如：
He is always frightened by ghost stories.
他总是被鬼故事吓坏。
Sally is terrified of cockroaches.
莎莉害怕蟑螂。
I am scared to talk in public.
我害怕在公共场合大声说话。
2. 而现在分词（以-ing结尾）用来谈论引起这种感觉的人、事或情况等，例如：
I watched a frightening movie, and now I can't .
我刚看了一部恐怖电影，现在睡不着。
Jackie touched a terrifying cat under the dinner table.
杰基摸着餐桌下一只可怕的猫。
3. 需要注意的是，scaring 不是分词形容词，通常用 scary 来代替，例如：
I think is going to be a scary thing for Nathan.
我觉得蹲监狱对于内森会是件很可怕的事。
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