形容词 + to 不定式

很多形容词后面可以接 to + 动词原形，用来说明某个动作怎么样，或者你对它有什么感受。主要有五种句型：

💡不要漏掉形式主语 it。英语句子必须有主语：It's difficult to learn English（不说：Is difficult to learn English）。

1. It's + 形容词 + to + 动词——对某个动作发表看法：easy、hard、difficult、important、necessary、possible、safe、dangerous、nice、great、expensive…

• It's important to drink enough water in hot weather.

  天热的时候多喝水很重要。

• It isn't easy to find a cheap flat in Hanoi.

  在河内找到便宜的房子不容易。

• It was great to see you last weekend!

  上周末见到你真是太好了！

也可以用 -ing 形式作主语来代替 it。意思一样，但用 it 的说法在口语中更自然：Finding a cheap flat isn't easy.

2. 加上做这件事的人：for + 人 + to + 动词

• It's hard for me to understand his accent.

  他的口音我很难听懂。

• It's normal for babies to wake up at night.

  婴儿夜里醒来是很正常的。

3. 评价某人的行为：It's + 形容词 + of + 人 + to + 动词——kind、nice、good、generous、thoughtful、silly、careless、rude…

• It's very kind of you to help me.

  你能帮我真是太好了。

• It was silly of me to leave my phone in the taxi.

  我真傻，把手机落在出租车上了。

4. 人 + 表示情绪的形容词 + to + 动词——某人对某事的反应：happy、glad、pleased、sorry、surprised、shocked、relieved、lucky、proud、disappointed…

• Nice to meet you.

  很高兴认识你。

• I'm sorry to hear that you're ill.

  听说你病了，我很难过。

• I was surprised to see Hung at the party.

  在聚会上见到阿雄，我很惊讶。

• We were lucky to get the last two tickets.

  我们很幸运，买到了最后两张票。

5. 人 + 表示态度的形容词 + to + 动词——准备好、不愿意、小心…：ready、willing、happy（= 乐意）、keen、afraid、careful、quick、slow…

• I'm ready to go.

  我准备好出发了。

• I'm happy to help if you need anything.

  你需要什么的话，我很乐意帮忙。

• Be careful not to drop it.

  小心别把它摔了。（否定：not to + 动词）

6. 物 + be + 形容词 + to + 动词——用它做某事有多容易、多难…。主语其实就是动词的宾语，所以句末不要再加 it/them。

• This book is easy to read.

  这本书很好读。（不说：easy to read it）

• His handwriting is hard to read.

  他的字很难认。

afraid：afraid to + 动词 = 害怕得不敢主动去做某事（I was afraid to ask）；afraid of + -ing = 害怕某事可能发生（I'm afraid of falling）。口语中两者常有重叠，但不带 of 的 afraid + -ing 是错的。I'm afraid (that)… 是委婉地告知坏消息的说法——见“口语句式”一课。

sorry：sorry to + 动词，用于正在发生的事或刚听到的消息（Sorry to bother you. / Sorry to hear that.）；sorry for + -ing 或 sorry (that) + 从句，用于你做过的事（Sorry for shouting.）。

• too + 形容词 + to + 动词 = 太……以至于不能：It's too hot to sleep. 见“‘too … to’ / ‘enough to’”一课。
• 形容词 + enough + to + 动词 = 足够……可以：She's old enough to drive.
• the first / the last / the only (+ 名词) + to + 动词 = 第一个、最后一个或唯一一个做某事的人：Lan was the first person to arrive. / He's the only one to pass the test.

• The tea is too hot to drink.

  茶太烫了，没法喝。

• Is your son old enough to ride a motorbike?

  你儿子到了可以骑摩托车的年龄吗？

• She was the last to leave the office.

  她是最后一个离开办公室的。

• ✗Is difficult to learn English.

  ✓It's difficult to learn English.

  英语需要形式主语 it。

• ✗It's hard for me understand his accent.

  ✓It's hard for me to understand his accent.

  for + 人后面仍然需要 to + 动词。

• ✗I'm ready for go now.

  ✓I'm ready to go now.

  ready + to + 动词；for 只接名词（ready for dinner）。

• ✗It's dangerous to driving at night.

  ✓It's dangerous to drive at night.

  to 后面接动词原形。

• ✗It's very kind for you to help me.

  ✓It's very kind of you to help me.

  称赞某人的行为 → of。

• ✗This question is easy to answer it.

  ✓This question is easy to answer.

  主语已经是宾语了，不要重复 it。