Imagine the first days in a new time zone. Slow to respond to the 28 , your body clock is confused. You're sleepy all day, but when it's time for bed, you can hardly fall asleep. Obviously you're  29 jet lag(时差反应).

Travelers have traditionally fought this 30 with sleeping pills or alcohol. There are actually healthier ways that can work just as 31 .

For example, the moment you get on the airplane, start 32 your biological block to the destination's time. If it's daytime in your destination, try to stay 33 . Walking around the cabin(客舱) can be of help. When it's nighttime, try to sleep. In that case，eat before the flight, 34 ;an empty stomach will prevent you from sleeping. These tips will help you start a new 35 of sleep and wakefulness.

1.

A flight

B change

C demand

D climate

解析：选B。B　考查名词词义辨析。根据下文提到的不良反应，是因为身体对时差反应慢了。

2.

A suffering from

B working on

C looking into

D leading to

解析：选A。A　考查动词短语辨析。suffer from 遭受；work on 从事；look into调查；lead to 导致。很明显，上文提到的不良反应是因为遭受到时差反应。

3.

A danger

B problem

C waste

D fear

解析：选B。B 考查名词辨析。A danger 危险性；B problem 问题；C waste浪费；D fear恐惧；句意：游客会用药片和酒精来处理这个问题。根据语境可知对待时差的问题，故选B项。

4.

A briefly

B slowly

C suddenly

D effectively

解析：选D。D 考查副词辨析。A briefly 简洁地； B slowly慢慢地； C suddenly 突然地； D effectively有效地；句意：这有几种健康的方法，并且很有效。根据语境可知选D项。

5.

A checking

B sending

C adjusting

D stopping

解析：选C。C 考查动词辨析。A checking 检查；B sending送到；C adjusting 调整；D stopping停止播送；句意：比如，在上飞机前，开始调整你的生物钟到你的目的的的时间。adjust to 把...调整到，故选C项。

6.

A awake

B alone

C hungry

D calm

解析：选A。A 考查形容词辨析。A awake B alone C hungry D calm句意：如果是白天到目的地，试着保持清醒。stay awake保持清醒，故选A项。

7.

A though

B so

C while

D or

解析：选B。B　考查连词词义辨析。词句两个分句之间是因果关系，故用 so。

8.

A understanding

B cycle

C research

D trend

解析：选B。B　考查名词词义辨析。这些方法能够帮你建立一个新的睡眠和清醒的循环。understanding理解；cycle循环；research研究；trend倾向。故选 B项。