How much sleep does a person need?【B1】the physiological bases of the need for sleep remain conjectural(猜想), rendering conclusive answers to this question impossible, much evidence has been gathered on how much sleep people do in fact obtain. Perhaps the most important conclusion to be【B2】from this evidence is【B3】there is great variability among individuals in total sleep time. For adults,【B4】between six and nine hours of sleep as a nightly average is not unusual, and 7.5 hours probably best expresses the norm. Such norms, of course, forms inevitably vary with the criteria of sleep employed. The most【B5】and reliable figures on sleep time, including those cited here, come from studies in sleep laboratories, where EEG criteria are employed. 【B6】consistently has been associated with the varying amount, quality, and pattern of electrophysiologically defined sleep. The newborn infant may spend an average of about 16 hours of each 24-hour period in sleep,【B7】the sleep time drops sharply; by two years of age, it may【B8】from nine to 12 hours. Decreases to approximately six hours have been observed among the elderly. 【B9】will be discussed from below, EEG sleep studies have indicated that sleep can be considered to consist of several different stages. Developmental changes in the relative proportion of sleep time【B10】in these sleep stages are as striking as age-related changes in total sleep time.
单选题 【B1】
【正确答案】 C
【答案解析】解析:做完形填空题往往需要"瞻前顾后"才能做出判断。本题必须要将句子下文看完才能确定答案。后面的much evidence has been gathered on how much sleep people do in fact obtain与前面提到的"睡眠心理基础并不明确"意思对立,因此选择含有"对比,让步"意思的连词while合理。despite虽然也能表达让步关系,却是介词,不能引导从句。
单选题 【B2】
【正确答案】 C
【答案解析】解析:本题要从动词搭配角度考虑。draw和conclusion形成习惯搭配。
单选题 【B3】
【正确答案】 D
【答案解析】解析:本题的考点是表语从句引导词,后面there be从句语义完整,无须任何添加,故选择一个起语法作用的引导词that即可。
单选题 【B4】
【正确答案】 C
【答案解析】解析:anything在此处表示某一范围内的不确定时间,其他词没有这样的用法。
单选题 【B5】
【正确答案】 B
【答案解析】解析:本题的关键是区别意思相关联的形容词用法。brief表示"简要的";precise表示"准确的";correct意思为"正确的";concise则为"简明的"。句子后半部分come from studies in sleep laboratories表示数字是来自实验室的,因此precise较为合理。
单选题 【B6】
【正确答案】 C
【答案解析】解析:从后面几个拓展句可知,睡眠的质、量和类型与年龄相关,因此只能选C。
单选题 【B7】
【正确答案】 C
【答案解析】解析:本题空白前半句说婴儿每天要用大量的时间睡眠,后面却说睡眠时间急剧减少,显然这里需要一个表示让步关系的连词。unless表示条件;however表示转折,但是副词;even if表示假设;although表示让步关系,符合要求。
单选题 【B8】
【正确答案】 B
【答案解析】解析:本题需要注意动词词义区别。extend,range,alter,rise分别表示"延伸","在…范围内变化","改变"和"上升"。本题相关部分要表达的是"从9到 12个小时变化",故选择range。
单选题 【B9】
【正确答案】 D
【答案解析】解析:本题空白处所缺词需具备双重作用:既作从句主语,又要指代后面句子的内容。只有as具备这种用法。
单选题 【B10】
【正确答案】 C
【答案解析】解析:此处所选项不能是谓语动词,因为后面已经有are as striking as...作谓语了。因此排除is spent和are spent。那么空白处内容只能是从属于前面sleep time的修饰成分。"所花的睡眠时间"不能用表示主动意思的spending,而spent含有完成、被动的意思,符合要求。