翻译下面的句子(Translate the sentences19-21)
19.Buses numbered 1 to 100 are limited to travel within the city centre.  _____________________________________________________________________
20. Los Angeles, which was built with the motor car in mind , and is famous for its six –lane highways ,is now the USA’s most congested city.
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21. A survey carried out at the end of 2003 suggests it does.
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