请先阅读下面短文，掌握其大意，然后用方框中所给的词的适当形式填空，并写在答题卡的相应位置。每个词限用一次。

     Many people have cars in the city. But pollution is a problem because of the____. Nowadays some downtown (市中心) areas around the world don't have cars. These car-free zones (无车区) are____ for people, bicycles, and public transportation only.

     Eight million people____ in the center of London and another two million people go to work there every day. The downtown area is very____ with hundreds of cars, buses, and taxis, but there are ____a lot of beautiful parks with free music concert. At lunchtime, many people go there for a rest ____ they get off work.

     Parts of Tokyo are always crowded with hundreds of people - but no cars! These modern car-free zones are____ popular and people like shopping there.

     In the past, Bogota was polluted because there____lots of cars and traffic. Now the downtown area is car-free zone and the air is____! Many people don't have a car and half a million people take the bus____. There are lots of stores. It's not expensive.

运用“追求真理是一个过程”的知识谈谈你对材料中“而此刻，我们才刚刚开始”的理解。