问题补充：
The United States is not part of the Kyoto Protocol.But since more than 1,000 mayors across the country have agreed to sign their own version of the protocol.
It is called the United States Conference of Mayors Climate Protection Agreement.Local leaders have agreed to follow the suggestions of the Kyoto Protocol in their communities.They have also agreed to urge state and federal governments to follow these suggestions.One goal is to reduce air pollution to the 1990 levels by .
A “green” city might work on several kinds of environmental goals and programs.These include air quality，reducing electricity use, green building, public health, the reuse of materials, water quality and clean transportation.
The Natural Resources Defense Council works to protect the environment through action, law and science.One of its online projects is called Smarter Cities, which lists some cities that have made important environmental steps.
Washington，D.C.is also a leading city for green roofs，with over 92,000 square meters of green rooftops.The city also launched a program called “Skip the Bag，Save the River.”Stores charge people a fivecent tax for using plastic or paper shopping bags instead of reusable bags.Money from the tax will be used to clean up a local river.
New York City is using water as a renewable energy source.For several years, the city has experimented with water in the East River to create energy.Officials operating the program recently asked for permission to put into place 30 river turbine devices.
The people of Portland, Oregon are among the top recyclers in the nation.People living there recycle over half of the waste they throw out.The city has also worked to provide green transportation by providing safe bike paths and free parking spaces where electric cars can get recharged.
In Oakland, California, you can ride on one of several public hydrogenpowered(氢气作燃料的) buses.These buses release zero pollution into the air.However，they cost about five times more than common buses.
【小题1】The United States Conference of Mayors Climate Protection Agreement is aimed at.A．reducing energy useB．reducing air pollutionC．improving public healthD．reusing waste materials【小题2】Why are shoppers charged a fivecent tax for buying shopping bags?A．To clean a local lake that has been polluted.B．To get enough money for the green roof project.C．To prevent shoppers from using reusable bags.D．To collect money for an environmental project.【小题3】New York City is cited as an example of.A．building green rooftopsB．making transportation cleanC．being good at recycling wasteD．using renewable energy source【小题4】Which of the following cities encourage citizens to use bicycles?
A．Washington，D.C. B．New York.
C．Portland. D．Oakland.
【小题5】One obvious disadvantage of adopting hydrogenpowered buses is.A．its high costB．side effectC．zero pollutionD．large spaceB
答案：
(答案→)B
解析：
【小题1】解析细节理解题。根据第二段的最后一句可知，the United States Conference of Mayors Climate Protection Agreement的主要目标之一是把空气污染的水平在前降低到1990年的水平。
答案B
【小题2】解析推理判断题。根据第五段的内容可知，华盛顿市向使用塑料袋和纸袋的购物者收5美分的税是为清理一条当地的河流筹款。
答案D
【小题3】解析推理判断题。根据第六段的内容可知，纽约市利用河水发电，是充分利用了可再生能源的范例。
答案D
【小题4】解析细节理解题。根据第七段的内容可知，美国Oregon州的Portland市鼓励市民骑自行车作为绿色出行的方式。
答案C
【小题5】解析细节理解题。根据第八段的内容可知，美国加利福尼亚州的Oakland市使用用氢气作燃料的公交车，虽然它们对空气无污染，但是造价是普通公交车的五倍，可见这种新型的环保公交费用相当高。
答案A
