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Some people think that in order to deal with the problem of congestion in cities, ______ vehicles should be banned in city centres while others consider this to be an unrealistic solution.

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The Saudi government is investing billions in __________ to support the enormous influx of people in Mecca.

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Visitors can wander around here without difficulty because most of the antique area is now a pedestrian __________.

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We must improve the environment through __________ design and greener buildings.

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All fossil fuels are ______ resources that cannot be replaced after use.

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People's lives will continue to be threatened ______ the continuous risk of earthquakes and tsunamis here.

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Eco-friendly transport systems will reduce greenhouse gas ______.

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In addition, more ______ zones for walking and cycle paths will be made available for people in all neighbourhoods.