三条铁律先刻进脑子：① 后接动词原形；② 三单不加 s；③ 否定后加 not，疑问把 can 提前。
功能
肯定
否定
疑问
能力（会/能）
I can swim.
I can't drive.
Can you ride a bike?
许可（可以/不准）
You can take photos.
You can't use the flash.
Can I open the window?
请求（请你……）
—（一般不说）
—
Can you help me? / Could you help me?
过去能力（过去会）
I could read at five.
I couldn't swim then.
Could you ride a bike?
can 与 could 的客气程度对比
说法
客气程度
场合
Can you help me?
一般（熟人/随意）
同学之间
Could you help me?
更礼貌（陌生人/车站）
问路、请人帮忙
Can I take photos?
询问许可
景点、博物馆
Could I have a ticket?
更礼貌的请求
售票窗口、餐厅
can 高频搭配小词块（口语直接搬）
功能
词块
意思
能力
can swim / can ride a bike / can cook
会游泳/骑车/做饭
许可
can take photos / can sit here / can go now
可以拍照/坐这儿/走了
请求
Can you help me? / Could you say that again?
你能帮我吗？/能再说一遍吗？
问路
Can/Could you tell me the way to...?
你能告诉我去……的路吗？
买票
Could I have a single/return ticket?
我要一张单程/往返票。
三个必背细节
① 后面永远原形：can swim（✗ can to swim / can swimming）。
② 三单不加 s：She can play（✗ She cans play）。
③ 否定/疑问靠 can 自己：can't = cannot；疑问把 can 提到主语前，动词仍原形。
⑤ 场景全解：伦敦街头怎么用 can/could（配图记忆）
场景
例句
记忆点
1 说能力
I can ride a bike, but I can't drive.
会/不会，后接原形
2 问许可
Can we take photos here?
景点拍照常用句
3 被告知不许
You can't use the flash.
can't = 不可以
4 请求帮忙
Could you tell me the way to the museum?
问路万能句，更礼貌
5 买票请求
Could I have a single ticket, please?
售票窗口礼貌句
6 过去能力
We could see a lot of places by underground.
could = 过去"能"
7 问价钱/买票
Can I get a return ticket? / Could you tell me the fare?
售票窗口常用
8 请求重复
Could you say that again, please? I didn't catch it.
没听清时救场句
can 和 could 不是"现在/过去"那么简单could 不一定是过去时：对陌生人客气请求时，"Could you help me?" 说的是现在的事，但语气更软。记住：真·过去能力用 could；客气请求也用 could，靠句意区分。
景点与售票窗口里的 can/could（跟读体会）
Guard: You can take photos here, but you can't use the flash. Visitor: Thanks. Could I also buy a ticket here? Guard: Sorry, you can't. You can buy one at the machine over there. Visitor: OK. Could you tell me how to use it? Guard: Sure, just press "single ticket".
can 的第三种意思：可能性A2 阶段先知道：can 还能表"有时候会"：Dogs can be dangerous.（狗有时候会很危险。）写作里偶尔用一句，显得词汇灵活。
⑥ 中国学生 5 大高频错误诊断
错误 1：三单给 can 加 s ✗ She cans swim very well. → ✓ She can swim very well. 口诀：情态动词自己不加 s。
错误 2：can 后面加 to ✗ I can to ride a bike. → ✓ I can ride a bike. can 后直接动词原形，不要 to。
错误 3：can 后面加 -ing ✗ He can playing football. → ✓ He can play football. 情态动词后永远原形，不进行、不三单。
错误 4：否定不会缩 ✗ He can not swim.（口语）→ ✓ He can't swim. / He cannot swim. 口语最常用 can't；cannot 是一个词。
错误 5：问路只会说 I want... ✗ I want you tell me the way. → ✓ Can/Could you tell me the way? 请人做事用 Can you...? 比 I want 礼貌地道。
⑦ KET 考点与真题演练
题型
怎么考
应对
Reading Part 4/5 完形
横线后是动词原形 → 前面填 can/can't
看句意选"能/不能"
Listening Part 1 选图
听 Can we...? 选"允许/不允许"的图
抓 can / can't 是肯还是否
Listening Part 3 对话
听请求与回应："Can I pay by card?"
抓请求句和 Yes/Sorry
Writing Part 6 便条
礼貌请求朋友做某事
用 Can you...? 开头
Speaking Part 1/2
说自己会/不会什么、礼貌请求
I can... / I can't... / Can you...?
真题风格演练（KET 出题方式）
真题风格 · Part 5完形填空：My sister is only five, but she (1) ___ already read. She (2) ___ ride a bike yet — it's too hard.
(1) can（会读）；(2) can't（yet 还不行，表不能）。
真题风格 · Part 1看图选句：博物馆里牌子写"No photos."。哪句对？A. You can take photos. B. You can't take photos. C. Can I take photos?
B。No photos = 不许拍照 = can't take photos。
真题风格 · Speaking礼貌请求：你想请路人告诉你去车站的路。怎么说？
参考：Excuse me, could you tell me the way to the station, please?（could 更礼貌，please 收尾）
真题风格 · Listening听对话："Can I pay by card?" — "Sorry, we can only take cash." —— 顾客能刷卡吗？
No, he can't.只能收现金（only take cash），不能刷卡。
真题风格 · Writing写便条请朋友帮忙：你想请他明天带你去车站（你不认路）。用 Can you...?
参考：Hi Jack, can you take me to the station tomorrow? I can't find the way. Thanks!
⑧ 背诵内容：10 个必备句型 + 问路请求模板
每天背 3 句，3 天背完。背的时候大声读，边读边想意思，别死记单词。
1. I can swim very fast. 我游泳很快。
2. I can't drive a car. 我不会开车。
3.Can you ride a bike? 你会骑自行车吗？
4.Can we take photos here? 这里可以拍照吗？
5. Sorry, you can't use the flash. 抱歉，不能用闪光灯。
6.Could you help me, please? 请问你能帮我一下吗？
7.Could you tell me the way to the museum? 您能告诉我去博物馆的路吗？
8.Could I have a single ticket? 我要一张单程票。
9. She could read when she was five. 她五岁就会读书了。
10. We couldn't find the bus stop. 我们找不到公交车站。
车站问路模板（KET Speaking 直接套）
Excuse me. Could you tell me the way to the National Museum? Can I take a bus there? … Thanks. Could I also have a single ticket, please? How much is it? … Great, thank you very much!
⑨ 口语练习：说出来才算会
练习 A · 跟读（2 分钟）
跟着上面背诵卡读 3 遍：第一遍慢读，第二遍正常速度，第三遍不看文字凭记忆说。注意 can't 要读清楚 /kɑːnt/，别和 can 混。
练习 B · 自我对话（3 分钟）
Q: Can you swim? → A: Yes, I can. / No, I can't.
Q: Can I open the window? → A: Yes, you can. / Sorry, you can't.
Q: Could you help me with this bag? → A: Of course I can.
练习 C · 挑战（2 分钟）
不用稿子，用 can/can't 说 5 句你会/不会做的事（游泳、骑车、开车、说英语）。再用 Could you...? 请别人帮你做一件事。录下来回听。
口语评分自查说完后对 3 条：① can 后面都是动词原形吗？② 没有加 s/to/ing 吗？③ 请求用 Could you...? 够礼貌吗？三条全过 = 这关过了。
三档进阶目标
🌱 入门：会说 I can swim / I can't drive。
🌿 熟练：会用 Can I...? 问许可、Can you...? 请人帮忙。
🌳 挑战：陌生人前用 Could you...? / Could I...?，并说清过去的事（I could... when I was...）。
⑩ 分层练习 15 题（含答案与解析）
基础 1改错：She cans swim very well.
She can swim very well. 情态动词不加 s。
基础 2改错：I can to ride a bike.
I can ride a bike. can 后不加 to。
基础 3填空：___ you speak English?
Can。问能力，疑问把 can 提前。
基础 4填否定：You ___ (not) park here.
can't / cannot。不许停车。
基础 5填空：I ___ swim when I was five.（过去会）
could。过去的能力用 could。
基础 6改疑问：You can tell me the way.
Can you tell me the way?
进阶 7选更礼貌的：___ you help me carry this bag? (Can / Could)
Could。请求陌生人/客气场合用 Could you...? 更礼貌。
进阶 8填空：We ___ find the bus stop yesterday.（找不到）
couldn't。过去"不能/没能"。
进阶 9改错：He can plays football after school.
He can play football. can 后用原形 play。
进阶 10翻译：请问这里可以拍照吗？
Excuse me, can I take photos here?
进阶 11完形（KET Part 5 风格）：At the museum, you (1) ___ take photos, but you (2) ___ use the flash.
(1) can（可以拍）；(2) can't（不许用闪光灯）。
挑战 12翻译：你五岁时会骑自行车吗？不，我不会。
Could you ride a bike when you were five? — No, I couldn't.
挑战 13补全对话：在售票窗口，你想买一张去伦敦的单程票，怎么开口？
参考：Excuse me, could I have a single ticket to London, please? How much is it?
挑战 14改错（3 处）：She can to drive. He cans speak French. Can you helping me?
① can to drive → can drive；② cans speak → can speak；③ Can you helping → Can you help。
挑战 15综合口语：用 3 句说你会/不会的事 + 1 句礼貌请求别人帮你。
参考：I can ride a bike, but I can't drive. I can speak a little English. Could you help me with this map, please?
⑪ 记忆口诀与 7 天复习计划
三句口诀
① 情态动词三不管：不加 s、不加 to、不加 -ing。
② can 是"现在能"，could 是"过去能"，could 也能更客气。
③ 否定 can't/couldn't，疑问 can/could 提前，后面动词全原形。