问题
单项选择题 A1型题
某年冬季，某地区居民因食用被甲肝病毒污染的毛蚶而发生甲型肝炎流行，此毛蚶称为（）
A.传染源
B.储存宿主
C.传播因素
D.传播机制
E.病原携带者
答案
参考答案：C
解析：
在外环境中参与传播病原体的因素称为传播因素，主要有空气、水、食物、土壤、用品和节肢动物等。
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某年冬季，某地区居民因食用被甲肝病毒污染的毛蚶而发生甲型肝炎流行，此毛蚶称为（）
A.传染源
B.储存宿主
C.传播因素
D.传播机制
E.病原携带者
参考答案：C
解析：
在外环境中参与传播病原体的因素称为传播因素，主要有空气、水、食物、土壤、用品和节肢动物等。
Hundreds of years ago, life was harder than it is today. People didn’t have modern machines. There was no medicine, either. Life today brings new problems. One of the biggest is pollution. Water polluti  on has made our rivers and lakes dirty. It kills our fish and pollutes our drinking water. Noise pollution makes us talk louder and we become angry more easily. Air pollution is t he most serious kind of pollution to all living things in the world.Cars, planes and factories all pollute our air every day. Sometimes the polluted air is very thick. People cannot see the sky clearly  .Many countries are making rules to fight against pollution. Factories now must clean their water before they throw it away. And they mustn’t let dirty smoke go into the air. There are many things we can do to fight against pollution. We should put waste things in dustbins and do not throw them on the ground. We should go to work by bike or on foot instead of taking a car or a bus. If there are fewer people driving, there will be less pollution. Ru  les are not enough. We should do our best to fight against pollution.小题1:Which of the following is NOT true about life in the past?
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