单选题 11.The rate at which a road wears depends on various factors, including climate, amount of traffic, and the size and weight of the vehicles using it. The only land transportation to Rittland's seaport is via a divided highway, one side carrying traffic to the seaport and one carrying traffic away from it. The side leading to the seaport has worn faster, even though each side has carried virtually the same amount of traffic, consisting mainly of large trucks.
Which of the following, if true, most helps to explain the difference in the rate of wear?

A、 The volume of traffic to and from Rittland's seaport has increased beyond the intended capacity of the highway that serves it.
B、 Wear on the highway that serves Rittland's seaport is considerably greater during the cold winter months.
C、 Wear on the side of the highway that leads to Rittland's seaport has encouraged people to take buses to the seaport rather than driving there in their own automobiles.
D、 A greater tonnage of goods is exported from Rittland's seaport than is imported through it.
E、 All of Rittland's automobiles are imported by ship.

【正确答案】 D

【答案解析】Argument Construction
Situation The side of a divided highway leading to a seaport has worn faster than the side leading away from the seaport. Both sides carry roughly the same amount of traffic, mainly consisting of large trucks.
Reasoning What could explain why the side of the highway leading to the seaport has worn faster than the other side? We are told that climate, amount of traffic, and the size and weight of vehicles on a road affect how quickly the road wears. We are also told that the amounts of traffic on the two sides of the highway are almost identical. Probably the climate on the two sides is also almost identical. Thus, the most likely explanation for the different rates of wear is that the size or weight of the vehicles driving on the two sides differs significantly. So any factor that would make the vehicles' size or weight greater on the side leading to the seaport than on the other side could help explain the difference in wearing.
A The increased traffic volume affects both sides of the highway, so it does not help explain why one side is wearing faster than the other.
B The winter weather affects both sides of the highway, so it does not help explain why one side is wearing faster than the other.
C The buses may contribute to wear on the side of the highway leading to the seaport, but not necessarily more than the car traffic they are replacing would (though the increased use of buses instead of cars may decrease the amount of traffic, buses would be heavier than cars and thus may result in an equal or greater amount of wear). Furthermore, the buses have to come back on the other side, probably carrying the returning travelers who have not left their cars at the airport.
D Correct. This suggests that the many trucks visiting the seaport tend to be more heavily laden with goods when traveling on the side of the highway leading to the seaport than when returning on the other side. The resulting difference in the trucks' weight when traveling on the two sides could explain the different rates of wear.
E These automobiles would be transported along the side of the highway leading from the seaport, but not along the side leading to it. This would likely create a pattern of wear opposite to the one observed.
The correct answer is D.