为什么Tomatoes are healthy food(西红柿是健康的食品 )Tomatoes 用复数,而Candy is a healthy food(糖果是健康的食品 )Candy用单数?

问题描述:

为什么Tomatoes are healthy food(西红柿是健康的食品 )Tomatoes 用复数,
而Candy is a healthy food(糖果是健康的食品 )Candy用单数?