Negative raising

Okay, so you know how sometimes we use the word "not" in a sentence to make it mean the opposite? Like if I say, "I am happy," but then I say, "I am not happy," it means I actually feel sad instead of happy.

Well, sometimes grown-ups use a fancy grammar thing called negative raising to make a sentence mean the opposite even when there's no "not" in it.

Let's say someone asks me, "Do you think your sister is coming to the party?" If I don't know for sure, I might say, "I don't think she is." But sometimes, people use negative raising and say, "I think she isn't."

That might sound confusing because usually "isn't" means "is not," which sounds like a negative. But here, it's being used to mean the same thing as "I don't think she is."

Basically, negative raising is a way of using grammar to make a sentence mean the opposite even when there's no "not" in it.