GRE阅读短文练习题(25)

In recent years, there has been a dramatic decline in the population of the shrike, a predatory bird that inhabits flat land, such as farms and pastures. Some ornithologists hypothesize that this decline is due to the introduction of new, more effective pesticides to control the insect species on which shrikes prey.

The answer to which of the following questions is NOT relevant to evaluating the ornithologists hypothesis?

Was there a decline in the shrike population before the new pesticides were first used?

Have shrike populations declined significantly in those habitats where the new pesticides have not been used?

Have the new pesticides more significantly reduced the population of insect species on which shrikes prey than did the pesticides previously used?

Are insects that have consumed the new pesti-cides more toxic to the shrikes that eat those insects than were insects that consumed the less effective pesticides?

Are the new pesticides considered by most people to be less harmful to the environment than the old pesticides were considered to be?