Cannot Have (Logical Impossibility)

This grammar is very simple to build. We use the word can't. This is the short version of cannot. In daily life, we almost always say can't. It sounds more natural. It sounds more like a real person talking. You combine can't with a base verb. The most common verbs are be and have. We use be for identity or location. "He can't be the thief!" We use have for possession. "You can't have my phone. It is in my pocket." The best part is the verb never changes. It does not matter if you say I, You, He, or They. The word can't stays the same. The verb after it stays the same. It is a very friendly rule for your brain. No complex endings to remember here!

1. 1Building these sentences is a three-step process.
2. 2Pick your subject. This is the person or thing you are talking about. Examples: I, She, The cat, My keys.
3. 3Add the word can't. This is your logic engine. It tells everyone you are sure.
4. 4Add the base verb. Use words like be, have, know, or see. Do not add to. Do not add -ing. Do not add -s.
5. 5Let's try it. Subject: It. Logic: can't. Verb: be. Result: "It can't be true!"
6. 6Another one. Subject: He. Logic: can't. Verb: have. Result: "He can't have the money. He is broke!"

Use this when you have strong evidence. Imagine you are ordering food. The waiter says they have no pizza. You see ten pizzas on the next table. You can say, "They can't be out of pizza. I see them right there!" You are using your eyes to prove a point.

Use it in job interviews too. If someone asks for a skill you don't have, you might say, "That can't be a requirement. The job ad didn't mention it." It shows you are paying attention.

Use it when asking directions. If a map says go left, but the road is blocked, you say, "The map can't be right. There is no road!"

It is perfect for everyday surprises. If your watch says 3 PM but the sun is setting, you say, "It can't be 3 PM!" Your brain is doing the math. It is matching what you know with what you see.

Do not use this for physical ability. If you don't know how to swim, you say, "I can't swim." That is about your skills. Logical impossibility is about the truth of a situation.

Also, do not use it for permission. If your mom says you are not allowed to go out, that is a different kind of "can't."

Avoid using can't for logic if you are only 50% sure. If you are just guessing, use might not. Only use can't when you feel like a judge in a court. You have the proof. You are ready to make a decision. Yes, even native speakers mess this up sometimes! They might say "It can't be" when they are just surprised. But for you, keep it for the "impossible" moments.

One big mistake is adding to. Never say "He can't to be here." That sounds very strange to an English ear. Just say "He can't be here."

Another mistake is using don't. Some people say "He doesn't can be..." This is a big no-no. can't is its own boss. It does not need do or does to help it.

Watch out for the s on the verb. Even for he, she, or it, we never say "She can't has." It must be "She can't have." It feels a bit weird at first. But you will get used to it quickly.

Lastly, don't confuse must not with can't. In logic, can't is for "impossible." Must not is often for rules. "You must not smoke here." Stick to can't for your logic puzzles.

How is can't different from isn't?

If you say "He isn't at home," you are just stating a fact.

If you say "He can't be at home," you are explaining *why* it is impossible. You might be looking at his house and seeing the lights are off. can't adds the power of your brain to the sentence.

Compare it to might not. "It might not rain" means maybe it will, maybe it won't. "It can't rain" means the sky is perfectly blue and there are no clouds in sight. One is a guess. The other is a conviction. Use can't when you want to sound strong and certain.