Our brain processes the world around us based on information that sensory organs (感官), including the eyes, pick up. For instance, when we see a cow or a horse standing behind a tree, we automatically "fill in" the part of the animal's body that is hidden from our sight. "So the brain is taking this kind of very sparse (匮乏的) information about the world and it's generating this rich world by filling in information," Stephen Macknik, scientist at the Barrow Neurological Institute in Arizona, US, told Science magazine.

But since our brains are filling in the gaps, sometimes they get it wrong. They tend to be driven by your previous experiences and you expect things to go as they have in the past even if sometimes they do not.This tendency explains magicians' success in fooling people with well-known coin tricks. For example, when you see a magician throw a coin up and down in one hand and then fake a coin throw to the other hand, you would naturally believe that the coin is in the other hand. Apart from the information gaps, magicians also use the "blind spots" theory when doing their shows. The most well known experiment demonstrating (证明) this theory is called the "invisible gorilla (大猩猩)", in which volunteers watch a video of two basketball teams. They are asked to count how many times the teams wearing white shirts pass the ball. In the meantime, a person dressed as a gorilla walks onto the court. But shockingly, half of the viewers don't notice the gorilla, even when they appear to be looking directly at it.

Magicians employ this tactic (招数), what they call "misdirection", in almost every one of their acts. They direct our attention somewhere else using comedy and music, which can make us miss stuff during the performance.

28. The magic trick is mentioned in the first paragraph to ______.

A. introduce the steps of the magic trick

B. prove magic tricks seldom go wrong

C. reveal how magic tricks are designed

D. get us to wonder how magicians trick the mind

29. We can conclude from the article that the human mind is easily fooled because our brain ______.

a. may have difficulty remembering what we just saw

b. fills in information about the real world

c. is influenced by our previous experiences

d. processes far more information than our sensory organs pick up

A. a, b B. b, c C. a, d D. c, d

30. During the "invisible gorilla" experiment, people watching the video ignore the "gorilla" because ______.

A. they don't look directly at it

B. they are not interested in it

C. they are too focused on counting

D. they consider it to be a distraction

31. Why do magicians usually use comedy and music when they play magic tricks?

A. To get viewers to stay focused on the show.

B. To make the show more fun and exciting.

C. To draw viewers' attention away from a secret action.

D. To create information gaps between magicians and viewers.