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 36 how quickly time has passed．

If you are familiar with this__37_,you'll know how time flies when you are having fun．And how time 38 when you are bored．Now scientists have 39 a reason why this is the case．

Scans have shown that patterns of activity in the brain_ 40 according to how we focus on a task．When we are 41 ．we concentrate more on how time is passingAnd this makes our brains_42_the clock is ticking more slowly．

In an experiment 43 by a French laboratory, 12 volunteers watched an image 44 researchers monitored their brain activity．The volunteers were told to 45 concentrate on how long an image appeared for, then 46 _the color of the image, and thirdly, study both duration（持续的时间） and color．The results showed that 47 was more active when the volunteers paid 48 subjects．

It is thought that if the brain is 　49　 focusing on many aspects of a task, it has to 50 its resources, and pays less attention to the clock．51 ,time passes without us really 52 it, and seems to go quickly．If the brain is not so active, it concentrates its__53___energies on monitoring the passing of time．__54_．time seems to drag．

Next time you feel bored__55__,perhaps you should pay more attention to what the teacher is saying!

36．A．guess　　　　 　 B．learn　　　　　 C．believe　　　 　　　 D．doubt

37．A．view　　　 　　　 B．point　　　　　 　　 C．scene　　　 　　　 D．experience

38．A．drags　　　　 B．stops　　　　 　　　　 C．backs　　　 　　　 D．gains

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

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

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

42．A．report　 　　　　 B．think　　　　　 　　 C．decide　 　　　　　　　 D．see

43．A．produced　 　　 B．carried　　　　　 C．tried　　　　　 　 D．performed

44．A．so　　　　　 　 B．when　　　　　 　　 C．while　　　　　 D．but

45．A．partly　　　 　　 B．quickly　　　　　 　 C．how　　　　　 D．first

46．A．remember　　 　 B．focus on　　　　　 C．forget　　　　 　 D．tell apart

47．A．the researchers B．the experiment　　 C．the clock　　　 D．the brain

48．A．much attention to　　　　　　　　　　　　　　　　　　　 B．more attention to 　　　　　　　　　　　　　

　　　 C．attention to many　 　　　　　　　　　　　　　　　　 D．attention to more

49．A．busy　　 　　　　 B．likely　　　　 　　　 C．ready　　 　　　　　 D．sure

50．A．focus　 　　　　　 B．gather　　　 　　 C．reach　　　　　　　 　　　　　　　　　　　　 D．spread

51．A．However　　 　 B．Furthermore 　　 C．Therefore　　　　 　　 D．Finally

52．A．recognizing 　　 B．watching　　 　 C．noticing　　　　　　 D．counting

53．A．enough　　 　　　 B．full　　　　 　　 C．right　　　　　　　 D．proper

54．A．In fact　　　 　 B．As a result　　 C．For example　　　 　　 D．Instead

55．A．in class　　 　　 B．with work　 　 C．in mind　　　　　　 　 D．of lessons

The twins are so much alike that their own mother can hardly ________.

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The twins are so much alike that it's difficult to tell them ____.

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