29. A. where            B. when          C. while             D. as

28. A. produced         B. carried out   C. tried             D. did

27. A. which            B. we            C. this              D. what

26. A. sleepy           B. bored         C. excited           D. active

25. A. change           B. develop       C. grow              D. slow

24. A. thought over     B. made up       C. suggested with    D. come up with

23. A. drags            B. stops         C. goes              D. backs

22. A. disappointed     B. satisfied     C. familiar          D. similar

21. A. slowly           B. quickly       C. terribly          D. foolishly

20. To tell you the truth; I really find__________ unbearable to work with such a terrible man as his brother.

A. which          B. it      C. that          D. what

You have waited 45 minutes for the valuable 10 minutes’ break between classes. But when the bell for the next class rings, you can’t believe how ___21__ time has passed.

If you are ___22___ with this scene, you’ll know how time flies when you are having fun and __23__ when you are bored. Now scientists have ___24___ a reason why this is the case.

Scans have shown that patterns of activity in the brain ___25___ according to how we focus on a task. When we are ___26___, we concentrate more on how time is passing. And ___27___ makes our brains think the clock is ticking more slowly.

In an experiment __28___ by a French laboratory, 12 volunteers watched an image __29___ researchers monitored their brain activity.

The volunteers were told to__30___ concentrate on how long an image appeared for, then ___31___  the color of the image, and thirdly, study both duration and color. The results showed that___32__ was more active when the volunteers paid attention to___33__ subjects.

It is thought__34____if the brain is focusing on many aspects of a task, it has to___35__ its resources, and pays less attention to the clock.__36__, time passes without us really__37__ it, and seems to go quickly. If the brain is not so active, it concentrates its___38___energies on monitoring the passing of time. __39__, time seems to drag.

Next time you feel bored___40___ , perhaps you should pay more attention to what the teacher is saying!