不定詞
不定詞的構成
不定詞是動詞的原型。在英語中，當我們談到不定詞時，一般指的是現在式不定詞，這是最常見的一種。然而還有其他四種型態不定詞：完成式型態的不定詞、完成進行式型態的不定詞、進行式型態的不定詞以及被動語態的不定詞。
不定詞又分為兩種型態：
- 帶 to 的不定詞 = to + 動詞原型
- 不帶 to 的不定詞（又稱「零不定詞」）= 動詞原型
現在式不定詞就是您在字典上會看到的動詞型態。
| 帶 to 的不定詞 | 零不定詞 |
|---|---|
| to sit | sit |
| to eat | eat |
| to have | have |
| to remember | remember |
否定型不定詞則是在任何型態的不定詞前加「not」即可。
舉例
- I decided not to go to London.
- He asked me not to be late.
- I'd like you not to sing so loudly.
- I'd rather not eat meat.
- I might not come.
帶 to 的不定詞的作用
帶 to 的不定詞用於很多句構上，通常表達某事的意圖，或者表達某人對某件事的看法。帶有 to 的不定詞可以接的動詞類型有很多，這部分可以參考接不定詞的動詞。
帶 to 的不定詞表明某動作的意圖或目的
在這種情況下，不定詞的 to 意思就跟 in order to 或 so as to 一樣。
舉例
- She came to collect her pay cheque.
- The three bears went to find firewood.
- I am calling to ask you about dad.
- You sister has gone to finish her homework.
帶 to 的不定詞用作句中的主詞
這是正式用法，多用於英語正式書寫上，口語上較少見。
舉例
- To be or not to be, that is the question.
- To know her is to love her.
- To visit the Grand Canyon is my life-long dream.
- To understand statistics, that is our aim.
帶 to 的不定詞表明某件事可以被用來做的事
在這種句型中，帶 to 的不定詞接著是名詞或代名詞。
舉例
- The children need a garden to play in.
- I would like a sandwich to eat.
- I don't have anything to wear.
- Would you like something to drink?
帶 to 的不定詞接在形容詞後
帶 to 的不定詞接在形容詞後的句型很常見，這類語句的公式如下：
主詞 + Be 動詞 + 形容詞 + (for/of 某人) + 帶 to 的不定詞 + (句子的其餘部分)
| 主詞 | + Be 動詞 | + 形容詞 | (+ for/of 某人) | + 帶 to 的不定詞 | (+ 句子的其餘部分) |
|---|---|---|---|---|---|
| It | is | good | to talk. | ||
| It | is | good | of you | to talk | to me. |
| It | is | important | to be patient. | ||
| It | is | important | for Jake | to be patient | with his little brother. |
| I | am | happy | to be | here. | |
| The dog | is | naughty | to destroy | our couch. |
評論某事時用帶 to 的不定詞
在對某個名詞評論時使用帶有 to 的不定詞，公式如下：
主詞 + Be 動詞 + 名詞片語 + 帶 to 的不定詞
| 主詞 | + Be 動詞 | + 名詞片語 | + 帶 to 的不定詞 |
|---|---|---|---|
| It | was | a stupid place | to park. |
| That | is | a dangerous way | to behave. |
| What you said | was | a rude thing | to say. |
| This | is | the right thing | to do. |
| Those | were | the wrong kind of eggs | to buy. |
| Jim | is | the best person | to hire. |
副詞和帶 to 的不定詞一起使用
帶 to 的不定詞經常與副詞 too 和 enough 一起用來表達滿意或不滿背後的原因。在句型上，too 和 enough 會被放在其修飾的形容詞、副詞或名詞的前面或後面，就如沒使用帶有 to 不定詞的方式一樣；接著在後面接帶 to 不定詞，表達數量或分量過多、充足或不足的理由。通常帶 to 不定詞以及後面接的所有字詞都可以移除，而剩餘的句子在文法上都還是正確的。
舉例
- There's too much sugar to put in this bowl.
- I had too many books to carry.
- This soup is too hot to eat.
- She was too tired to work.
- He arrived too late to see the actors.
- I've had enough food to eat.
- She's old enough to make up her own mind.
- There isn't enough snow to ski on.
- You're not old enough to have grand-children!
帶 to 不定詞和疑問詞一起使用
ask、decide、explain、forget、know、show、tell、understand 等動詞可以接在 where、how、what、who、when 等疑問詞後，加帶 to 不定詞即可。
舉例
- She asked me how to use the washing machine.
- Do you understand what to do?
- Tell me when to press the button.
- I've forgotten where to put this little screw.
- I'm not sure I know who to call.
零不定詞（不帶 to 的不定詞）的作用
零不定詞接在助動詞後
舉例
- She can't speak to you.
- He should give her some money.
- Shall I talk to him?
- Would you like a cup of coffee?
- I might stay another night in the hotel.
- They must leave before 10.00 a.m.
零不定詞用在感知動詞後
與感知動詞一起使用，句型為動詞 + 受詞 + 零不定詞。
舉例
- He saw her fall from the cliff.
- We heard them close the door.
- They saw us walk toward the lake.
- She felt the spider crawl up her leg.
零不定詞用在 make 和 let 等動詞後
舉例
- Her parents let her stay out late.
- Let's go to the cinema tonight.
- You made me come with you.
- Don't make me study that boring grammar book!
零不定詞用在 had better 的措辭後
舉例
- We had better take some warm clothing.
- She had better ask him not to come.
- We had better reserve a room in the hotel.
- You'd better give me your address.
- They had better work harder on their homework.
零不定詞用在疑問詞 why 後
在表達建議時，疑問詞 why 後會接零不定詞。
舉例
- Why wait until tomorrow?
- Why not ask him now?
- Why leave before the end of the game?
- Why walk when we can go in the car?
- Why not buy a new bed?