在农田、果园里长期使用农药，会发现农药灭虫的效果越来越差，这

【名词&注释】

高锰酸钾(potassium permanganate)、矿泉水(mineral water)、自然选择(natural selection)、蒸馏水(distilled water)、稀有气体(noble gas)、长期使用(long-term use)、时间表(schedule)、剩余物(remainder)、技术落后(lag in technology)、抗药性。

[单选题]在农田、果园里长期使用农药，会发现农药灭虫的效果越来越差，这是因为有些害虫产生了抗药性。害虫产生抗药性的原因是( )

A. 害虫对农药进行选择的结果
B. 遗传的结果
C. 喷洒技术落后^{(lag in technology)}的结果
D. 自然选择的结果

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学习资料：

[单选题]BIt seems that travelling is very important in modern(现代的)life． The fastest way of trav- elling is by plane． You can travel by plane in one day to a place that it took a month or more to

B. But it has its advantages(优势)． You can enjoy the scenery of the places you're travelling through． Modern trains have comfortable seats and．dining cars．
C. There are large liners or river boats． You can visit many other countries and different parts of your country on them． Ships are not so fast as trains or planes ,but travelling by sea is a very pleasant way to spend a holiday．Many people like to travel by car． You can make your own timetable(时间表^(schedule))． You can travel three or four hundred miles or only fifty or one hundred miles a day ,just as you like．You can stop wherever you wish-at a place where there is something interesting to see ,at a good restaurant where you can enjoy a good meal ,or at a hotel to spend the night． That is why trav-elling by car is popular for pleasant trips ,while people usually take trains or planes when they are travelling on business．
D. From the passage ,we know the fastest(最快的)way of travelling is _________ ．
E. by sea
F. by train
G. by car
H. by plane

[单选题]下列物质属于纯净物的是（ ）

A. 从空气中分离得到的稀有气体
B. 经过沉淀，过滤后得到的矿泉水
C. 高锰酸钾加热完全分解后的剩余物^(remainder)
D. 部分结晶的蒸馏水

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