不可数名词用is。
不可数名词属于单数,不过两个不可数名词用and连起来,就成复数要用are了。
不可数名词一般可视为单数,如Time is money中的time.针对food一词,在The food in the fridge IS not enough一句中用单三,但在These kinds of food WERE never available when she was young中,虽然food为句子的逻辑主语,但语法主语为kinds,kind可数,所以谓语be跟随kind的复数形式kinds变成were。