The Underground(地鐵)

      These years you can see many underground railways are being built in some big cities.  Underground railway is both convenient and fast. The underground railway is also called "the

tube","the subway'or "the underground". There're lifts for you to  go  up  or  down.   The  trains'  doors  open  and  close automatically. In Shanghai, during rush hours the underground arrives at the station every two minutes.  But with too many people taking  the  underground,  people  find  it  really  too crowded. Maybe Shanghai needs more underground railways.