单选题 11. Samples taken from the ice of glaciers show that during the last ice age there was far more dust in the atmosphere than there is now. Since greater amounts of dust in the atmosphere would result in less sunlight's reaching the Earth's surface, it is likely that the large amount of dust then present helped maintain low global temperatures and thus prolonged the ice age.
Which of the following, if true, most seriously weaken the argument? ______

A、 Large amount of dust in the atmosphere would tend to keep heat from the Sun that reached the Earth's surface from escaping into outer space.
B、 The glacial samples show that during the period between the two most recent ice ages the level of atmospheric dust was far lower than it was during either of ice ages.
C、 Volcanic eruptions in the recent past have released sufficient dust to cause detectable changes in global temperature patterns.
D、 The amount of dust in the atmosphere was significantly greater in the middle of the last ice age than at the end.
E、 Sunlight is the main heat source of the Earth's surface.

【正确答案】 A

【答案解析】 A：灰尘有加热的作用，削弱了原文灰尘会降温的观点，故正确。
B：该选项可以说明冰河时代比其他时代的尘土数量多，说明尘土和冰河时代可能有关系，加强了原文。
C：该选项也加强了灰尘影响冰川时代的观点。
D：不需要将冰河时代的不同阶段进行区分。
E：阳光是热源+尘埃可以阻挡阳光→地球变冷，加强了原文，故不选。