Things like Hula hoops（呼啦圈）used to be very popular．Did you ever own any of these？If you didn't，don't feel too bad．They were all fads．A fad is something that becomes very（36） 　 　among a large number of people，but only for a short time．（37） 　 　can become a fad very quickly，but can stop being popular just as quickly．（38） 　 　it is no longer "cool，"a fad goes away．Anything can become a（n） （39） 　 　﹣fashion，food，music，technology，even language．

In the late 1970s，Erno Rubik，a professor was looking for a （40） 　 　way to teach his students about 3D objects．He （41） 　 　a six﹣color plastic object that would be called the Rubik's Cube（魔方）．The goal was to get each side of the cube a （42） 　 　color．It was very challenging．It took a few years for the toy to become popular，but then （43） 　 　，in 1982，it seemed everyone had one．People bought over a hundred million of the （44） 　 　．There were 50books available that year offering solutions（解决办法）．Then，just as suddenly as the craze （风尚） started，it （45） 　 　．By 1983，people were not interested in the Rubik's Cube anymore，perhaps because so many people（46） 　 　had one in their home．

In 2012，a South Korean musician named Psy released a song called "Gangnam （江南） Style．"The music video shows Psy pretending （假装） to horse﹣ride while he is dancing．In six months，it became the first Youtube （一视频网站） video ever to reach a billion views （观看）．Six months after that，（47） 　 　went on to reach two billion views．The song and video started a worldwide （48） 　 　craze．"Gangnam Style" had a huge influence on world popular culture．U．S．President Barack Obama and U．K．Prime Minister David Cameron even （49） 　 　the dance．"Gangnam Style" became less and less popular，（50） 　 　the "Korean Wave" of culture remains popular all over the world．

36．A．useful	B．popular	C．valuable	D．relaxing
37．A．Both	B．Someone	C．Something	D．None
38．A．Although	B．Whether	C．Before	D．When
39．A．invention	B．fad	C．goal	D．dream
40．A．creative	B．difficult	C．traditional	D．common
41．A．found	B．bought	C．invented	D．borrowed
42．A．strange	B．dark	C．bright	D．different
43．A．suddenly	B．slowly	C．exactly	D．seriously
44．A．videos	B．toys	C．clothes	D．books
45．A．spread	B．appeared	C．ended	D．failed
46．A．already	B．hardly	C．especially	D．only
47．A．he	B．they	C．we	D．it
48．A．food	B．dance	C．language	D．sport
49．A．depended on	B．tried out	C．gave up	D．put off
50．A．then	B．and	C．but	D．so．