填空题

Sleep is divided into periods of so-called REM sleep, characterized by rapid eye movements and dreaming, and longer periods of non-REM sleep.　　kind of sleep is at all well-understood, but REM sleep is　　to serve some restorative function of the brain. The purpose of non-REM sleep is even more　　. The new experiments, such as those　　for the first time at a recent meeting of the Society for Sleep Research in Minneapolis, suggest fascinating explanationsof non-REM sleep. 　　For example, it has long been known that total sleepis 100 percent fatal to rats, yet, examination of the dead bodies, the animals look completely normal. A researcher has now　　the mystery of why the animals die. The rats　　bacterial infections of the blood,　　their immune systems the self-protecting mechanism against diseases―had crashed.

【参考答案】

B

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填空题

The standardized educational or psychological tests that are widely used to aid in selecting, classifying, assigning ,or promoting students, employees, and military personnel have been the target of recent attacks in books, magazines, the daily press, and even in Congress. 71. The target is wrong, for in attacking the tests, critics divert attention from the fault that lies with illinformed or incompetent users. The tests themselves are merely tools, with characteristics that can be measured with reasonable precision under specified conditions. Whether the results will be valuable, meaningless, or even misleading depends partly upon the tool itself but largely upon the user.All informed predictions of future performance are based upon some knowledge of relevant past performance: school grades, research productivity, sales records, or whatever is appropriate. 72. How well the predictions will be validated by later performance depends upon the amount, reliability, and appropriateness of the information used and on the skill and wisdom with which it is always interpreted. Anyone who keeps careful score knows that the information available is always incomplete and that the predictions are always subject to error.Standardized tests should be considered in this context. They provide a quick, objective method of getting some kinds of information about what a person learned, the skills he has developed, or the kind of person he is. The information so obtained has, qualitatively, the same advantages and shortcomings as other kinds of information. 73.Whether to use tests, other kinds of information, or both in a particular situation depends, therefore, upon the evidence from experience concerning comparative validity and upon such factors as cost and availability.74. In general, the tests work most effectively when the qualities to be measured can be most precisely defined and least effectively when what is to be measured or predicted can not be well defined. Properly used, they provide a rapid means of getting comparable information about many people. Sometimes they identify students whose high potential has not been previously recognized, but there are many things they do not do. 75. For example, they do not compensate for gross social inequality, and thus do not tell how able an underprivileged youngster might have been had he grown up under more favorable circumstances.

单项选择题

The word it ( line 3, para. 2) most probably refers to________________.

A． the lack of stable communities
B． the breakdown of informal information channels
C． the increased mobility of families
D． the growing number of people moving from place to place