The passage asserts which of the following about the exposures involved in the “research on olfactory adaptation”?

　　A. The exposures are of long enough duration for researchers to investigate many aspects of olfactory adaptation.

　　B. The exposures have rarely consisted of reexposures following extended absences from the odorous environment.

　　C. The exposures are intended to reproduce the relatively transient olfactory changes typical of exposures to odors in natural environments.

　　D. Those exposures of relatively short duration are often insufficient to produce the phenomenon of receptor fatigue in study subjects.

　　E. Those exposures lasting several hours produce reductions in receptors in the olfactory epithelium that are similar to the reductions caused by prolonged odor stimulation.

　　答案是

　　A ----对应在文章中第二段第一句话的后半句里。

　　错误选项

　　B ----混!串层到第一段的最后一句去了。

　　C ----混!串层到第一段的第二句了。

　　D ----反!与原文第二段倒数第二句说反了。

　　E ----无!

　　当你对自己的答案不确定时可用排除法排除另外四个选项，但无一能逃出这四种类型!好好总结下每一道题。