"My brother can swim better than I" is grammatically correct here, though colloquially "better than me" might sound more natural. At any rate, the correct grammar should be one of the acceptable answers!
I am from Russia, so I have a question. Is this sentence correct?: "My brother can swim better than I do."
Yes. The verb can be left out - it is understood - but the sentence works with either "...than I do" or "...than I."
Actually this sounds odd to me. I would say "My brother can swim better than I can." or "My brother swims better than I do."
So have I. It's still not accepted.
Not accepted 12/15/20, reported once again.
Not accepted 1/25/21
"My brother knows how to swim better than I do" is not accepted. :(
So what is the meaning? Does my brother know better than I know? Or does my brother swim better than I swim. Technically my brother can know how to swim but if he is paralyzed, he is going to drown.
My brother can swim better than I can. Using me this way is grammatically incorrect.