问题 选择题

动物在维持生态平衡中起重要作用的原因是(  )

A.动物的呼吸作用能为植物的光合作用提供二氧化碳

B.动物能促进物质循环,维持了物质的供求平衡

C.动物能为植物传粉、传播种子,保证了植物的数量,保证了生态平衡

D.动物在食物链中担任不同的营养级别

答案

动物在生态平衡中起着重要的作用:食物链和食物网中的各种生物之间存在着相互依赖、相互制约的关系.在生态系统中各种生物的数量和所占的比例总是维持在相对稳定的状态,这种现象叫做生态平衡.生态系统中的物质和能量就是沿着食物链和食物网流动的,如果食物链或食物网中的某一环节出了问题,就会影响到整个生态系统,而动物作为消费者,在食物链中的位置不同,担任的营养级别也不同,对维持生态平衡具有重要的作用.

故选:D

阅读理解

E  

Many children first learn the value of money by receiving an allowance. The purpose is to let children learn from experience at an age when financial mistakes are not very costly.

The amount of money that parents give to their children to spend as they wish differs from family to family. Timing is another consideration. Some children get a weekly allowance. Others get a monthly allowance.

In any case, parents should make clear what, if anything, the child is expected to pay for with the money. At first, young children may spend all of their allowance soon after they receive it. If they do this, they will learn the hard way that spending must be done within a budget. Parents are usually advised not to offer more money until the next allowance.

The object is to show young people that a budget demands choices between spending and saving. Older children may be responsible enough to save money for larger costs, like clothing or electronics. Many people who have written on the subject of allowances say it is not a good idea to pay your child for work around the home. These jobs are a normal part of family life.

Paying children to do extra work around the house, however, can be useful. It can even provide an understanding of how a business works.

Allowances give children a chance to experience the three things they can do with money. They can share it in the form of gifts or giving to a good cause. They can spend it by buying things they want. Or they can save it.

Saving helps children understand that costly goals require sacrifice: you have to cut costs and plan for the future. Requiring children to save part of their allowance can also open the door to future saving and investing. Many banks offer services to help children and teenagers learn about personal finance. A savings account is an excellent way to learn about the power of compound interest.

Compounding works by paying interest on interest. So, for example, one dollar invested at two percent interest for two years will earn two cents in the first year. The second year, the money will earn two percent of one dollar and two cents, and so on. That may not seem like a lot. But over time it adds up.

77.For children who receive allowances, they’d better not ________.  

A. waste money to buy gifts for their parents or friends  

B. buy their favorite clothing or electronics for themselves  

C. save money like their parents or other adults  

D. ask for the next allowance before the decided date.

78.Many parents give children an allowance regularly to ______.  

A. meet children’s basic need for life       

B. give control over their children  

C. see whether they have financial mistakes  

D. help children learn how to manage money

79.If children are required to save their allowance, they ______.  

A. can experience three things related to money  

B. can understand the relation between goals and sacrifice  

C. will do more work around the house  

D. help themselves found the basis for their future life

80. What is the best title for the passage?

A. Be Generous to Pay Your Children

B. Be Wise to Avoid Financial Mistakes

C. Saving Allowances Does Good to Children

D. Allowances Help Children Learn about Money

单项选择题