Here are the most important modal verbs with their meanings:
|CAN||Ability||I can play the piano|
|Permission||Can I go out tonight?|
|Offer||Can I help?|
|COULD||Past ability||He could already speak three languages when he was 10.|
|Past permission||He could go to the party.|
|Probability (40%)||It could get worse before it gets better.|
|Request||Could you help me with this email?|
|MAY||Probability (50%)||I may need to fly to the States.|
|Permission||May I ask you a question?|
|Offer||May I help?|
|MIGHT||Probability (35% or less)||The parcel might arrive today.|
|MUST||Prohibition||You mustn’t go on to the site without protective clothing.|
|Probability (100%)||That must be our new CEO. I recognise him from the picture on the website.|
|SHOULD||Advice||You shouldn’t speak to him when he’s stressed.|
|Offers||Should I bring you some lunch back from the baker’s?|
|SHALL||Offers||Shall I bring you some lunch back from the baker’s?|
|Suggestions||Shall we go for a drink after work?|
|WILL||Prediction||I think she will get the job this time|
|Spontaneous decision||The phone is ringing. I’ll answer it.
orThe phone is ringing. I can answer it.
|Request||Will you help me?|
|Promise||I will help you when I get back.|
Forming questions and negatives with modal verbs
We don’t need an auxiliary verb (do, did, does etc.) to form questions and negatives with modal verbs.
- Can you check my emails when I’m away? (Not: Do you can check my emails when I’m away?)
- I can’t dance. (Not: I don’t can dance.)
Future and past forms of can
Another way of saying “I can” is “I am able to”
- I can speak French = I am able to speak French.
- You can speak French = You are able to speak French
The past form of “can” is either “could” or “was / were able to”.
The future form of “can” is “will be able to”
- I can speak French very well.
- I am able to speak French very well.
- I could speak French very well when I was younger.
- I was able to speak French very well when I was younger.
Tip: Because “could” can also has other meanings (see above), we often use “was / were able to” to express the past of can in positive sentences. For example, “I was able to finish all the work” is more normal than “I could finish all the work”, whereas “I wasn’t able to finish all the work” is equally normal as “I couldn’t finish all the work.”
- I will be able to speak French very well when I have finished my French course.
Past and future forms of must
Another way of saying “I must” is “I have to”
- I must speak to the boss = I have to speak to the boss.
- You must speak to the boss = You have to speak to the boss.
The past form of “must” is “had to”.
The future form of “must” is “will have to”
- I must speak to the boss.
- I have to speak to the boss.
- I had to speak to the boss yesterday.
- I will have to speak to the boss if I don’t understand.
Mustn’t or don’t have to?
The negative form of “must” is “don’t have to” (or do not have to)
- I don’t have to speak to the boss because I understand everything.
- You don’t have to do all the photocopying because I have already done it.
“Mustn’t” (or must not) = not allowed to
- You mustn’t drive through a red light.
- You mustn’t drink and drive.