Most students have no trouble making a sentence such as this one:
My dog is bigger than your dog.
But then, they make mistakes with sentences such as this one:
At McDonald's, US sizes are much bigger than Japan.
Huh? What are you comparing? In the first sentence, you are comparing your dog with my dog. In the second sentence, you are comparing US sizes with Japanese sizes. So, you need to use "Japanese sizes" at the end of the sentence. Or you can do this:
At McDonald's, US sizes are bigger than Japanese ones.
Do you know how to use these?
His voice is louder than mine.
Where are you going to stay, at my house or his?
Our team practices more often than theirs.