[请教]Reading:89-05-Passage4-Q6

closedeyes

Here in the United States, before agricultural activities destroyed the natural balance, there were great migrations of Rocky Mountain locusts (Melanoplus spretus). Great migrating hordes of these insects once darkened the skies on the plains east of the Rockies where crops were often destroyed; the worst years were those from 1874 to 1877. One of these migrating swarms was estimated to contain 124 billion locusts. During another migration in Nebraska it was estimated that the swarm of locusts averaged half a mile high and was 100 miles wide and 300 miles long. Usually, these swarms take oft from the ground against the wind, but, once airborne, they turn and fly with it. warm convection currents help to lift them, often to great heights. During the great locust plagues the situation in Nebraska became so serious that the original state constitution had to be rewritten to take care of the economic problems. The new document was known as "The Grasshopper Constitution." It is now believed that these locusts were a migratory form or phase of the lesser migratory locust, which is still common there. In this respect, the North American migratory locusts resemble their African relatives. In both regions the migratory forms arise as a result of crowding and climatic factors. Migratory forms are apparently natural adaptations which bring about dispersal when locust populations become too crowded. Fortunately for our farmers the migratory form - - the so-called spretus species - - no longer seems to occur regularly, although there was a serious outbreak as late as 1938 in mid-western United States and Canada. Actually, there is no reason why the destructive migratory form might not again appear if circumstances should become favorable.

6. Which of the following is NOT mentioned in the passage as influencing the migration of locusts?

A)    Darkness

(B)   Agricultural activities

(C)  Warm air currents

(D)  Overcrowding

正确答案是A。

我做的时候原文定位在蓝色字体，这样A和B我都无法排除，请大家指点。

springqi

A和B之间考虑, 与B相关的一句话是: Here in the United States, before agricultural activities destroyed the natural balance, there were great migrations of Rocky Mountain locusts (Melanoplus spretus).与A相关的一句话是--Great migrating hordes of these insects once darkened the skies. 可见, A是蝗虫造成的影响,而不是什么影响了蝗虫~~其实看到这句话,就晓得选A了~~IS NOT MENTIONED as influencing the migration of locusts

springqi

两个都不能确定的时候,选一个最不对的~~

I MEAN 最与题相符合的, 剩下一个考试的时候不用考量那么多~~节省时间~~

[此贴子已经被作者于2005-7-2 11:30:11编辑过]

closedeyes

以下是引用smileqi在2005-7-2 11:29:00的发言：

两个都不能确定的时候,选一个最不对的~~

谢谢解答，有道理。觉得TOEFL阅读好奇怪的说，经常出现其实都不是准确选项，只能选一个最沾边的情况。

springqi

9494,听力也常常是两个选项看似都对,只能选一个最对的~~呵