题干

小明在体育用品专店购买篮球时发现,随着羽毛球拍供应量的增加,羽毛球的供应量也随之增加。这是因为
①羽毛球拍与羽毛球是互补商品                      
②羽毛球拍与羽毛球互为替代品 
③某商品需求量增加,其互替品的需求量会随之减少 
④某商品需求量增加,其互补商品的需求量会随之增加

A:①②

B:①④

C:②③

D:③④

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答案(点此获取答案解析)

B

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    Today, many people use plants from other places to design their yards. Well, do they have any influence on animals living nearby? As we know, plants supply food for things like insects and plant-eating animals. In turn, birds and meat-eating animals feed on these insects and plant-eating animals. It is easy to see how important plants are.

    Although foreign plants may look beautiful, they can cause problems when there are too many of them. I live in Virginia, USA, and sometimes see a plant—commonly known as Kudzu—that seems to cover everything in the area, even climbing over whole trees and houses.

    Kudzu is an unbelievable plant since it grows very fast. It was first brought to the United States from south-east Asia around the 1870's as a crop that farmers could grow. However, Kudzu quickly came to be considered harmful throughout the southern United States.

    Since Kudzu grows fast in many different environments, it can completely cover areas of land quickly. The plant is also not eaten by any insects or birds in the United States so it can grow unchecked. Kudzu can cover trees, bushes, and even houses. It costs the United States 500 million dollars a year to just keep Kudzu from growing too fast. The plant is a perfect example of what scientists call an invasive (侵略性的) species, which grows more quickly than other native plants.

    All foreign plants have the possibility to spread quickly. Not only are they costly, but planting them in gardens actually takes away food from insects. If everyone filled their garden with plants native to where they live, many lovely butterflies and other native creatures would be attracted to their backyards! So, take a look out of your window — how does your garden grow?