题目：
Before refrigerators were invented, the next best thing was an ice box. But another way to keep food fresh is to use an evaporative cooler. A common design is a tall box with several shelves inside to hold the food. The shelves are pieces of metal with many small holes through them. The sides of the box are covered with pieces of thick cloth.
Containers of water are placed at the top and bottom of the cooler. The ends of each piece of cloth lie in the water so the cloth stays wet.
The cooler is put outdoors, but not in the sun. Air will pass through the wet cloth. The inside of the box will stay several degrees cooler than the outside air temperature. And this may be cool enough to keep foods fresh, at least for a short time.
Some foods can make you sick if they are stored in conditions that are not cold enough to prevent the growth of harmful organisms（微生物）. Freezing can keep some foods in good condition for months after the growing season, ____________________ if they are kept too cold.
Some fruits and vegetables must be stored at zero to four degrees Celsius. Any colder, and they might be damaged. Some foods need to be stored at four to eight degrees, and some need to be stored above eight degrees for best results.
Wet the fruits and vegetables so they do not become too dry. The best time to do this is before storage. Cover the items in plastic once they reach the right "critical temperature" for storage. Most fruits and vegetables need the relative humidity（湿度）in Storage to be kept between eighty-five and ninety-five percent.
Finally, leave space between the food containers and the walls of the cold storage area so air can flow. Keep the space clean. And try not to open the doors too often.
小题1:What is the main idea of the text?（no more than 8 words）
____________________________________________________________
小题2:Complete the following statement with proper words.（no more than 3 words）
You would be ill if you eat some foods that are kept in such a hot place that more __________ grow.
小题3:Fill in the blank in Paragraph 4 with proper words.（no more than 5 words）
____________________________________________________________
小题4:Why should we wet fruits and vegetables before storage?（no more than 11 words）
____________________________________________________________
小题5:What does the word "this"（Line 2, Paragraph 6）probably refer to?（no more than 5 words）
____________________________________________________________
答案：
小题1:How to keep food fresh in coolers.
小题2:harmful organisms
小题3:Yet foods can be damaged
小题4:In order not to let them become dry. /Because most fruits and vegetables need the relative humidity in storage.
小题5:Wetting the fruits and vegetables.
题目分析：在冰箱发明之前人们是怎样保鲜食物呢？在文中作者介绍了一种名为an evaporative cooler，即蒸发冷却器的器皿。其中一种普通的设计就是一个内置几个金属架子，而周围都围着厚布的高箱子。此外作者还介绍了这种冷却器的具体使用方法。
小题1:文章开头通过refrigerators、 an ice box.引出使食物保鲜的另一种方法，即another way to keep food fresh is to use an evaporative cooler.，然后文章围绕cooler具体的结构及使用方法展开行文，由此可知文章中心内容是介绍如何利用冷藏器来使食物保鲜的，所以答案是 How to keep food fresh in coolers.
小题2:根据文章第四段Some foods can make you sick if they are stored in conditions that are not cold enough to prevent the growth of harmful organisms可知在温暖环境下致病的有害微生物会大量繁殖，所以此处填harmful organisms。
小题3:根据下文内容可知水果蔬菜以及有些食品都是有最佳储存温度的，温度太低会使食物受到破坏，即Any colder, and they might be damaged. 由此可知，此空填Yet foods can be damaged
小题4:根据文章倒数第二段Wet the fruits and vegetables so they do not become too dry.可知在保存前把水果蔬菜弄湿为的是保持水分，答案为In order not to let them become dry. /Because most fruits and vegetables need the relative humidity in storage。
小题5:根据上文Wet the fruits and vegetables so they do not become too dry.可知此处this指代把水果弄湿这件事，所以答案填Wetting the fruits and vegetables.
