It couldn't/can't be him! It's too early.

[MichaelLu2000]

This website says that "couldn't" cannot be used to express present or future impossibilities while "could" can be used to refer to present or future possibilities.

https://www.englishcoursemalta.com/learn/can-cant-could-couldnt/

I think about it, and it's indeed weird to see "couldn't" in sentences like:

He just began practicing karate last week. He couldn't beat a blackbelt. (should be can't)
It couldn't be him! It's too early. (should be can't)
It couldn't rain tonight. (should be won't)
If we didn't work together, we couldn't win the game. (should be wouldn't be able to)
If it rained, I couldn't go to your place (should be wouldn't be able to)

Is what this website says true?

 

[jutfrank]

Is what this website says true?

I won't say it's untrue, but it's not very clear. It's true that you shouldn't use couldn't for future possibility.

I think about it, and it's indeed weird to see "couldn't" in sentences like:

He just began practicing karate last week. He couldn't beat a blackbelt. (should be can't)
It couldn't be him! It's too early. (should be can't)
It couldn't rain tonight. (should be won't)
If we didn't work together, we couldn't win the game. (should be wouldn't be able to)
If it rained, I couldn't go to your place (should be wouldn't be able to)

Where did you find these?

 

[yiirtoola]

Not a teacher

"He just began practicing karate last week. He couldn't beat a blackbelt." - In this context, "couldn't" is used correctly to express the idea that he is not capable of beating a blackbelt at the present time.
"It couldn't be him! It's too early." - This usage of "couldn't" is correct. It means it is impossible for it to be him due to the time factor.
"It couldn't rain tonight." - This sentence is also correct. It implies that it's impossible for it to rain tonight.
"If we didn't work together, we couldn't win the game." - This usage is accurate. It means that without working together, winning the game is impossible.
"If it rained, I couldn't go to your place." - This sentence is also correct. It means that if it rained, the speaker would be unable to go to your place.

 

[yiirtoola]

While this sentence is grammatically correct, it might not convey the intended meaning. The use of "couldn't" in this sentence implies that if it were to rain, the speaker would be physically incapable of going to the other person's place. It suggests that rain would somehow prevent them from going.

 

[jutfrank]

"He just began practicing karate last week. He couldn't beat a blackbelt." - In this context, "couldn't" is used correctly to express the idea that he is not capable of beating a blackbelt at the present time.

Right.

"It couldn't be him! It's too early." - This usage of "couldn't" is correct. It means it is impossible for it to be him due to the time factor.

I say this isn't correct. You mean can't.

"It couldn't rain tonight." - This sentence is also correct. It implies that it's impossible for it to rain tonight.

I'm not sure about that one, either.

"If we didn't work together, we couldn't win the game." - This usage is accurate. It means that without working together, winning the game is impossible.
"If it rained, I couldn't go to your place." - This sentence is also correct. It means that if it rained, the speaker would be unable to go to your place.

I agree with both of those.

Did you get those opinions from an AI tool, @yiirtoola?

 

[emsr2d2]

He couldn't beat a blackbelt.

This sentence is what I like to call an "implied conditional".

He couldn't beat a blackbelt if he fought one today.

 

[Rover_KE]

@yiirtoola, as you are not a teacher, you will need to state that clearly in every post. When you've made ten posts you will be able to add that to a signature line, as White Hat has done in post #13 here.