You can stay here ____ you don’t make a loud noise.
A. unless
B. so long as

Note: What is wrong with A?
Can I say “you will have to leave unless you behave.”

Question

You can stay here ____ you don’t make a loud noise.
A.	unless
B.	so long as

Note: What is wrong with A?
Can I say “you will have to leave unless you behave.”

Answer

The first sentence would only make sense if you change it to "You can stay here unless you make a loud noise."
"You will have to leave unless you behave," is fine. Also, "You can stay here as long as you behave (yourself)."

Answer

When you say, A, unless B, you mean A, except in the case of B. So by using "unless" in your first sentence, you would be saying "you can stay here ONLY IF you make a loud noise." That is because unless + don't is a double negative, which in English makes it a positive statement.

Answer

as long as