問題詳情


(B)It is estimated that the number of cars in the world will have tripled to nearly 1.5billion by 2020. How can we have this number of cars without severely polluting theenvironment? Every couple of years, a French tire company sponsors a challenge tothe world’s car makers to come up with cleaner, “greener” vehicles. Green vehiclesprovide an alternative to traditional fuel-powered vehicles, and pose less hazard tothe purity of the air we breathe. The most common green vehicles at the moment are hybrids, or cars that use amix of fuel power and electrical power to improve fuel economy. The gas-poweredengine makes the car move, but it also generates electricity, which powers the electricengine that works as its partner. There are also completely electric vehicles, which atfirst glance would seem to be extremely clean since they do not produce anyemissions. However, the electricity to operate them comes from traditional electricalsources, which also release environmentally harmful gases into the air. Some cars have been built to run on cleaner fuels such as natural gas and ethanol.These fuels used to be hard to find but they are becoming more readily available todrivers. Another green alternative that may be popular in the future is powered byhydrogen, which combines with oxygen in the air to produce a reaction that powersthe motor. The problem is that it takes about 11.6 liters of hydrogen to create the sameamount of power as one liter of fuel. Hydrogen is not always easy to obtain by theaverage consumer, and cars that run on hydrogen do not yet have the widespreadfueling stations needed to allow for long-distance travel.These cleaner fueling alternatives are very appealing, but they come with a fewdrawbacks. One problem is that as cars become more fuel-efficient, performancetends to suffer. Automobile performance is measured by two characteristics: torqueand horsepower. Torque is the ability to pull weight; horsepower is how fast a car cango. Engineers are constantly working hard to produce cleaner modes of transportationthat function as well as traditional vehicles do. Most of the people who are drivinggreen machines today are willing to sacrifice performance for the benefits to theenvironment, but the average consumer does not want to buy a car that does not haveas much torque or horsepower as what he or she is accustomed to.
54. What is this passage mainly about?
(A) Air pollution.
(B) Green vehicles.
(C) Car manufacturers.
(D) Environmental protection.

參考答案

答案：B
難度：適中0.444444
統計：A(4),B(16),C(3),D(11),E(0)

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