Each one of us shares this planet with seven billion others．And we all need （36） 　 : 　．People and products need to move from city to city and country to country．However，we all know（37） 　 　most cars，motorcycles，boats and planes cause air pollution．They are also（38） 　 　．This is a serious problem in many cities．（39） 　 　inventors are coming up with creative ideas to try to reduce the pollution and noise．

In many cities around the world，motorcycles are very（40） 　 　．Now Vietnam has around 33million motorcycles and China has almost 120 million．Motorcycles are a faster and cheaper way to get around a city than（41） 　 　．Yet air pollution is a growing problem．In large cities，people（42） 　 　it is difficult to breathe．To solve these problems，a U．S．company designed an environmentally friendly motorcycle，It uses electricity as fuel（燃料）．As a result，there is（43） 　 　pollution．It's also quiet and fast．This makes （44） 　 　a good choice for getting around a city．

The Italian city of Venice is a city with only a few（45） 　 　．There are no cars in the city center．（46） 　 　cars，water taxis and buses carry people along the city's canal（运河）．However，they cause pollution，（47） 　 　to the water．English engineers Dick and Jem designed a solar﹣powered（太阳能）water taxi．The water taxi

（48） 　 　run for a day after being recharged（充电）．

Planes also cause air and noise pollution．Designing an environmentally friendly airplane is a real （49） 　 　．Some airplane companies have （50） 　 　to solve the problems．Swiss engineers have gone one step further．They developed a solar airplane．This plane holds the world record for the longest solar﹣powered flight﹣1，541 kilometers from Arizona to Texas in America．

36．A．air	B．food	C．transportation	D．communication
37．A．how	B．why	C．when	D．that
38．A．noisy	B．dirty	C．fast	D．expensive
39．A．Since	B．So	C．Because	D．Although
40．A．popular	B．valuable	C．dangerous	D．safe
41．A．bikes	B．subways	C．buses	D．cars
42．A．explain	B．complain	C．doubt	D．promise
43．A．much	B．some	C．no	D．more
44．A．them	B．you	C．us	D．it
45．A．rivers	B．roads	C．tourists	D．people
46．A．Instead of	B．Thanks to	C．Because of	D．As for
47．A．probably	B．only	C．especially	D．hardly
48．A．must	B．can	C．should	D．need
49．A．question	B．job	C．decision	D．challenge
50．A．disagreed	B．refused	C．started	D．remembered．