사전 찾아봐도 접속사 뜻은 없는 거 같은데ㅠㅠ
Like your other muscles, when it’s in shape, it will be able to work better so that you’ll have more energy. Besides [it works/working] better, your heart may also work longer if you exercise.
여기서 왜 답이 working인지 알려줄 수 있을까?ㅠㅠ