18．
Human civilization has truly come a long way．From using animals for transport to the super fast automobiles that we have today．From using flint to making fire to using one touch lighters．But there are some things that we will never let go of．Some ancient traditions that have been brought down through the ages are still followed today．
Groundhog Day（土拔鼠节），falls on the 2nd of February every year．It is observed in the United States and Canada．While this day may be a public holiday and a bank holiday，it is not a compulsory holiday declared by the government．But this is not so for all the states．State-wise holidays may vary．
Ever heard of Punxsutawney Phil？Groundhog Day is observed because of this groundhog．The day is indeed about a groundhog．Punxsutawney is the name of an apparently weather forecasting groundhog．He lives in his burrow（洞穴）on Gobler's Knob，Punxsutawney in Pennsylvania，for a short period before the 2nd of February every year．On the 2nd of February，Phil comes out from his burrow and looks for his shadow．If he sees his shadow and goes back into the burrow，then America will have an extended winter of six weeks，But if he cannot see his shadow，and he remains outside．It means winter will soon end and spring will arrive very shortly．Phil has been‘predicting'the length of winter in this manner for almost a century and they have always been almost 100% accurate．
Groundhog Day is celebrated in some parts of the USA and Canada．The largest celebration is held at Punxsutawney，Pennsylvania．People come in scores to visit Punxsutawney Phil．They wait eagerly，camping days in advance，to see the small groundhog appear from his burrow，check for his shadow and either go back in or stay out．People cheer when they hear it is time for winter to end and celebrate by eating sweets and singing and dancing．Today．the Groundhog Day is a widespread tradition and an exciting event．
46．People celebrate Groundhog Day becauseC．
A．some sweets are provided on Groundhog Day
B．more and more people love groundhogs
C．the groundhog predicts the beginning of spring
D．Punxsutawney Phil is worth respecting
47．What does the author intend to tell us in Paragraph 1？B
A．Human civilization has a long history．
B．Some old traditions should be carried on．
C．Human civilization develops very fast．
D．Some old traditions have disappeared．
48．We learn from the passage that Punxsutawney PhilA．
A．forecasts the weather based on his shadow
B．witnesses the history of human development
C．organizes celebrations on Groundhog Day
D．gives performances on Groundhog Day
49．We may infer from the passage thatC．
A．groundhogs will replace TV weathermen soon
B．groundhogs can forecast the weather accurately
C．Groundhog Day is becoming popular in the US and Canada
D．a longer shadow of a groundhog indicates a longer winter
50．Which of the following statements is true according to the passage？D
A．Winter will end if the groundhog goes back into the burrow．
B．Groundhog Day is a compulsory'holiday in the US and Canada．
C．A groundhog will remain outside if he sees his shadows on 2
nd，Feb．
D．The celebration in Punxsutawney attracts large numbers of visitors．
