三相星形接线中性点不接地的电源系统，当发生一相接地时，三个线电压（）。 A.不变 B

第二卷
第四部分：写作（共三节, 满分40分）
第一节阅读填空（共10小题; 每小题1分，满分10分）
阅读短文，根据所读内容, 在下表中的空格处填上适当的单词和短语，每空不超过3个单词。
Animals seem to have the sense to eat when they are hungry and they do not eat more than their bodies need. It has been proved that rats will, when given a choice over a period of time, prefer water with vitamins to water without vitamins even though there is no difference in taste or smell between the two water bottles. When a fragrant flavor（香味）was added to the vitamin-enriched water, the rat did seem to develop a taste for it and kept drinking it even after the vitamins were switched to the clear water. In time, however, they broke the habit and went back to where the necessary vitamins were.
In a classic experiment, babies of 6 to 12 months old were placed in a cafeteria（自助餐厅） feeding arrangement, with a wide selection of baby food before them. They were given what ever food they pointed to or appeared interested in. We are told that at first they showed some unusual eating patterns, but that over a period of time they managed to select well-balanced diet.
So, in selecting food, rats and babies do seem to know and act on what’s best for them. Obviously, there is a ‘body wisdom’, which humans soon lose. Most of us do not eat as wisely as we could. Many of our food preferences are culturally determined and influenced by long-established habits. Some people eat fox, dog and blackbirds, while we eat cows and pigs. So what people eat and how much they eat seems to be greatly influenced by what is going on around us.
Research on eating habits

76._______	To find out the relationship between the need of the body and eating.
78._______	Subjects	Ways	77.
	Rats	●Given two water bottles   without difference in 79.________. ●80.   __ water with fragrant flavor and water with vitamins.	●81. _  water with vitamins to water without vitamins. ●Drink water with fragrant flavor first, then turn to water 82.      __  .
	83.         of 6-12 months	Given whatever they pointed to or were interested in.	84.__   unusual eating patterns at first, later select a well-balanced diet.
Conclusion	Rats and babies have a 85.   ____   in selecting food.