So it might be that, if you went to a French restaurant and you looked through it and you found they only had margarine and they didn't have butter, you could say, "Ah, I see what's wrong with them.
Así podría ser que, si fueran a un restaurant francés y observaran entre sus cosas y encontrasen que solamente tienen margarina y no manteca, podrían decir, "Ah, ya sé lo que tienen mal.