food在什么时候是可数名词

　　例句：

　　They are at the end of their food supply.

　　他们的食物储备已消耗殆尽。

　　Within three days they had exhausted their supply of food.

　　他们在三天之内就把所有粮食吃光了。

　　His company offers a flexible packaging service for the food industry.

　　他的公司为食品工业提供灵活的.`包装服务。

　　It seems such a waste to throw good food away.

　　把好的食物扔掉似乎太浪费了。英语可数名词一般指普通名词中人或物的个体，能与不定冠词a，an连用并且能够计数的名词，以及部分人或物的总称，不可数名词通常是指不能够计数的人或物。