18．
Look at the center circles of Picture 1．Which of the centre circles looks larger？
Take a first look and you probably think that the centre circle in Diagram A is smaller than that in Diagram B．In fact，they are exactly the same size．
Then look at the picture 2above．What do you see？A vase（花瓶） or two faces？Does the picture change quickly from one to the other again and again？Maybe or maybe not，but you can never see them at the same time．
"What's happening？Is something wrong with my eyes？"You may wonder at what you see．Don't worry．Here is how it goes：
When we look at things，our eyes send messages to our brains and then our brains interpret （解讀） the information．However，sometimes our brains interpret the received information in a wrong way．It seems that our eyes are playing a joke on us．This often happens and we call it"Visual illusion"（視覺錯(cuò)誤）．
Movie makers often make use of visual illusions．They make the objects around actors much smaller or bigger than usual．This makes us believe that the actors are much larger or smaller than they usually are．The movies Jurassic Park and Honey I shrunk（縮�。� the kids just make use of visual illusions．
23．What's the right order according to the passage？A
a．We look at things with our eyes．b．Our brains interpret the messages．
c．Our brains tell us what we have seen．d．Our eyes send messages to our brains．
A．a(chǎn)dbc
B．cabd
C．a(chǎn)cdb
D．bcad
24．Movie makers make use of visual illusions toD．
A．help the actors look better
B．make the actors much braver
C．help the actors become stronger
D．make the actors seem different in size
25．In the following picture，it seems that Line AB is shorter than Line CD，but in fact Line AB is as long as Line CD．Which paragraph can explain what has happened to our eyes？C
A．The second one．
B．The third one．
C．The fifth one．
D．The sixth one．
