Most people who travel long distances complain of jetlag(时差反应). Jetlag
makes business travelers less productive (对产的，有成效的) and more prone {{U}}(51)
{{/U}} making mistakes. It is actually caused by {{U}}(52) {{/U}} of
your "body clock"-a small cluster(串、组、群)of brain cells that controls the timing
of biological {{U}}(53) {{/U}}. The body clock is designed for a regular
rhythm(节奏)of daylight and darkness, so that it is thrown out of balance when it
experiences daylight and darkness at the "wrong" times in a new time zone. The
{{U}}(54) {{/U}} of jetlag often persist(持续) for days {{U}}(55)
{{/U}} the internal body clock slowly adjusts to the new time
zone. Now a new anti-jetlag system is available that is based on
proven, {{U}}(56) {{/U}} and pioneering scientific research. Dr. Martin
Moore has devised a practical strategy to adjust the body clock much sooner to
the new time zone {{U}}(57) {{/U}} controlled exposure to bright light.
The time zone shift(转换) is easy to accomplish and eliminates (消除) {{U}}(58)
{{/U}} of the discomfort of jetlag. A successful time zone
shift depends on knowing the exact times to either {{U}}(59) {{/U}} or
avoid bright light. Exposure to light at the wrong time can actually make jetlag
worse. The proper schedule {{U}}(60) {{/U}} light exposure depends a
great deal on {{U}}(61) {{/U}} travel plans. Data on a
specific flight itinerary (旅行路线) and the individual's sleep {{U}}(62)
{{/U}} are used to produce a trip guide with {{U}}(63) {{/U}} on
exactly when to be exposed to bright light. When the trip guide
calls {{U}}(64) {{/U}} bright light you should spend time outdoors if
possible. If it is dark outside, or the weather is bad, {{U}}(65) {{/U}}
you are on an air plane, you can use a special light device to provide the
necessary light stimulus(刺激) for a range of activities such as reading, watching
TV or working.
【答案解析】[解析] 本题考查的是名词搭配与辨析。symptoms的意思是“症状，病症”；symptoms persist for days症状持续好几天；diseases“疾病(时差反应不是真正的病)”；signs"征兆，迹象”，虽然也可指病症，但是并不能表示某种反应的表现；defects意为“缺点，过失，欠缺”。与题意不符。
【答案解析】[解析] 本题考查的是对表示程度的不定代词的掌握。空格所在的句子说摩尔博士设计的方法可以很容易地完成对新时区的调整，因此它可以eliminate most of the discomfort of the jetlag，消除时差反应带来的大部分不适。B项与C项都与该句意思相反，而D项是比较级，但原句中并没有出现与之相比较的词。