I couldn't go to school because I was sick.
I wasn't able to go to school because I was sick.
They can speak English perfectly.
They are able to speak English perfectly.
She couldn't visit her grandma because she was too busy.
She wasn't able to visit her grandma because she was too busy.
He can go to your party today.
He is able to go to your party today.
She couldn't sleep last night.
She wasn't able to sleep last night.
We couldn't cook pizza.
We weren't able to cook pizza.
He can run very fast.
He is able to run very fast.
I couldn't swim when I was younger.
I wasn't able to swim when I was younger.
We can't go out today because it is going to rain.
We aren't able to go out today because it is going to rain.
We can speak German fluenty.
We are able to speak German fluently.
He can't perfom in school plays.
He isn't able to perform in school plays.
