听力原文： Going through cities and villages, I was attracted by Swedish national flags flying over houses and buildings which were ordinary family houses and offices. I noticed that on the road, all the cars' headlights were turned on even under the sun of June. Mr. Raiding explained that according to the new traffic regulations, drivers were required to keep the lights on day and night, which helped decrease the traffic accidents. Along both sides of the road, there were high fences used to keep the animals living in the forests from rushing onto the road. I could see little bare land in the country. In fact, fifty-four percent of the land is covered by forests and another ten percent by lakes and rivers. I was told that in Sweden nobody has the right to lay the land bare -- whoever cuts the trees Or spoils the grass must restore it right away. Whenever trees are cut, they are replaced by young trees at once.
Around Sweden, there is a notice in the bathroom of every hotel, which reads: "We care for our environment." In Sweden, you cannot see rubbish in streets, public gardens, rivers or lakes. The bottles are made of glass and the packages are made of paper or other natural materials which can be recycled. To make best use of their resources, Swedes never turn on the heating too high or the air-condition too low. The indoor temperature is always kept around twenty-five degrees Centigrade, no matter at home or in large hotels.
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A. Because it would help decrease traffic accidents.
Because it was a Swedish custom.
C. Because it was always very dark in Sweden.
D. Because it was always cloudy and rainy in Sweden.