Is my sentence is proper English?
You should stop playing basketal untill, you bring up your grade.You can't have your cake and eat it too, you have to sacrifice something.
Thank you so much for your response.
It's not. This is more like "if you don't eat your meat, you can't have any pudding."
On the one hand, he is upset that he is behind his class because playing basketball is time-consuming, on the other hand, he doesn't like to quit playing basketball because he don't like to let his friends down.
I"d say it's more like "Something got to give."
"You can't marry the richest woman in the world and still be considered the most eligible bachelor in the world." That's an example of not having your cake and eating it too.
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.