Scientists are learning more about our
need for sleep. Most people sleep{{U}} (26) {{/U}}eight hours each
night.{{U}} (27) {{/U}}people sleep more than{{U}} (28)
{{/U}}and others sleep as{{U}} (29) {{/U}}as two or three hours each
night. Scientists do not know exactly{{U}} (30) {{/U}}some people sleep
more than others. Dr. Ernest Hartman has a (an){{U}} (31) {{/U}}about
this. He believes that the{{U}} (32) {{/U}}of sleep depends on how a
person{{U}} (33) {{/U}}problems. He said people who need only a few{{U}}
(34) {{/U}}sleep usually are people who have much energy and make good
use of{{U}} (35) {{/U}}to get their work to be done quickly.{{U}}
(36) {{/U}}he said many people who sleep longer than normal do
creative work and seem to need{{U}} (37) {{/U}}dreaming time to find
solution{{U}} (38) {{/U}}emotional problems. Some scientists agree{{U}}
(39) {{/U}}this idea and others dispute. To determine
the{{U}} (40) {{/U}}of the lack of sleep, scientists have put{{U}}
(41) {{/U}}through a set of psychological and performance tests{{U}}
(42) {{/U}}them, for instance, to add columns of numbers or recite a
passage read to them only minutes earlier, "We've found that if you're in
sleep{{U}} (43) {{/U}}, performance suffers," says Dr. David.
"Short-term memory is{{U}} (44) {{/U}},{{U}} (45) {{/U}}are
abilities to make decisions and to concentrate."
【答案解析】此题考查的是代词that的用法：that可以代替上文提到的人或事，其复数形式为those。例如：I know there's a problem，but I haven't got time to worry about that now．这里的that代替的是事。再如：Why don't you ask Ken? That's who I would choose．这里的that代替的是人。在这句里，that代替的是eight hours这个时间段。因此，正确答案是B项。
【正确答案】
C
【答案解析】此题考查的是as...as结构，表示“和……一样”，其中两个as中间应该使用形容词或副词的原形，因此我们可以直接排除B项longer。由于two or three hours是可数名词，又可以接着排除much和little。所以C项为正确答案。
【正确答案】
B
【答案解析】此题考查的是know后宾语从句的引导词。我们很容易能够排除how和when。部分同学可能会选择that，将其代入句中就成了“Scientists do not know exactly that some people sleep more than others．”即“科学家们并不十分清楚一些入睡得比其他人久这件事。”这显然和原文意义不符，故排除A项。将why代入空白处，则意义符合逻辑，即“科学家们并不十分清楚为什么一些人睡得比其他人久”。所以B项为正确答案。
【正确答案】
B
【答案解析】此题考查的是与“想法”相关的几个词的辨析。thinking表示“想法、看法”是不可数名词，所以这里应排除A项。idea是可数名词，常用于have an idea这个结构。suggestion是不可数名词，所以C项也应排除。ponder“沉思”是动词，可用于ponderon/over/about结构中，因此D项也应排除。所以B项是正确答案。
【正确答案】
A
【答案解析】此题考查的是表示时间的量的说法。amount一般和不可数名词连用，表示“……的量”，如a large amount of time。period表示“时期、周期”，和原文意义不符，故排除B项。stage“阶段”，也应排除。number一般与可数名词连用，如a number of students，因此D项也应被排除。所以A项为正确答案。
【答案解析】本题考查的是习惯搭配。agree后可以接的介词有on/about和with，但用法有所不同。“agree on/about”表示“对某事达成一致意见”，例如：The committee members agreed on the need for more information．意为“委员会成员就需要更多信息一事达成了一致意见。”“agree with”表示“赞同”，例如：I don't agree with corporal punishment in schools．意为“我不赞同在学校里进行体罚。”而本句的意义是“一些科学家并不赞同这一看法”，所以问题应该选择B项。