不一定所有食物都必须是新鲜的。干果和罐头水果也是很好的备选食品，而冷冻食品通常比某些冷藏食品更富含维生素。所以人们不仅要常食用新鲜食物，还要备有脱水、罐装和冷冻食物。
Not everything has to be fresh either. Dried and canned fruits are a great standby, while frozen product often has a higher vitamin content than something that’s been kept in your fridge. So use fresh ingredients regularly, as well as having dried, canned and frozen foods to hand.
(Source: wwenglish.com)