基礎 · Unit 33
助動詞 (can / may)
can 和 may 是助動詞，所以形態不隨主詞改變，後面一定要接原形動詞，can 表示能力·請求·許可，may 表示禮貌的許可·微弱的推測。
概念說明
can 和 may 是助動詞，所以形態不隨主詞改變，後面一定要接原形動詞，can 表示能力·請求·許可，may 表示禮貌的許可·微弱的推測。
A. can — 能力·請求·許可
can 是助動詞，所以主詞是第三人稱單數時形態也不變，後面一定要接原形動詞。can + 原形動詞 這一個形式就能表達能力、請求、許可三種意思。
| 用途 | 意思 | 例句 |
|---|---|---|
| 能力 | 能夠~ | I can swim. |
| 請求 | 可以~嗎？ | Can you open the door? |
| 許可 | 可以~ | You can sit here. |
| 否定 (can't) | 不能~ / 不可以~ | I can't speak Japanese. |
- She can play the piano very well. (她鋼琴彈得非常好。)
- Can you pass me the salt? (可以把鹽遞給我嗎？)
- You can borrow my umbrella. (你可以借我的雨傘。)
- I can't drive a car yet. (我還不會開車。)
B. may — 許可·微弱的推測
may 表示比 can 更正式的許可，以及「可能~」這種微弱的推測。推測用法在機率大約一半左右時用起來最自然，否定形不太用縮寫，所以寫成 may not 兩個字。
| 用途 | 意思 | 例句 |
|---|---|---|
| 許可 (禮貌) | 可以~嗎？ | May I come in? |
| 許可 (肯定) | 可以~ | You may leave now. |
| 微弱的推測 | 可能~ | It may snow tonight. |
| 否定的推測 | 可能不~ | She may not come today. |
- May I ask a question? (我可以問一個問題嗎？)
- You may sit down. (你可以坐下。)
- The train may be late. (火車可能會誤點。)
- He may not remember me. (他可能不記得我了。)
C. be able to — can 的時態延伸
be able to 和 can 一樣是「能力」的意思，但它不是助動詞而是 be 動詞句型，所以能自由地和過去式·未來式·現在完成式結合。尤其想帶出過去實際上「做到了」這種語感時，was/were able to 會比 could 自然。
| 時態 | can | be able to |
|---|---|---|
| 現在 | I can swim. | I am able to swim. |
| 過去 | I could swim as a kid. | I was able to finish it yesterday. |
| 未來 | (無) | I will be able to speak French soon. |
| 現在完成 | (無) | I have been able to sleep well lately. |
- She is able to lift heavy boxes. (她能夠搬起很重的箱子。)
- We were able to catch the last train. (我們趕上了最後一班火車。)
- You will be able to understand it soon. (你很快就能理解了。)
- I haven't been able to reach him all day. (我一整天都聯絡不上他。)
重點整理
- 1can 和 may 都是助動詞，形態不隨主詞改變，後面一定要接原形動詞。(例: She can swim. — She cans swim. 是錯的)
- 2can 兼具能力·請求·許可三種意思，may 則主要用在禮貌的許可和微弱的推測(可能~)。(例: Can you help? / It may rain.)
- 3be able to 和 can 意思相同，但時態結合很自由，可以用在過去式·未來式·現在完成式。(例: I will be able to speak French.)
- 4想帶出過去實際上「做到了」的語感時，was/were able to 比 could 自然。(例: We were able to catch the last train.)
- 5may not 實際上沒有縮寫形態(mayn't)，所以就用兩個字原樣寫出來。(例: She may not come.)
例句
I can speak three languages.
我會說三種語言。
She can play the guitar very well.
她吉他彈得非常好。
Can you help me with this box?
你可以幫我搬這個箱子嗎？
You can borrow my pen if you need it.
你需要的話可以借我的筆。
I can't come to the meeting tomorrow.
我明天不能去開會。
這個單元還有更多例句。註冊後可以看完整內容並聆聽發音。
容易犯的錯誤
She can swim.
I can speak Korean.
He may come later.
I will be able to help you tomorrow.
You may not smoke here.