번역:Sugar is sweet.
The 슈가는 안되나요?? 여기 the 엄청 좋아하시는것 같던데
In the situation, we already know whats the sugar. we can say the sugar is sweet or this sugar is sweet. But, in this sentence "설탕은 달다" We just say about general sugar. So you don't use "the sugar" is sweet