Electric cars may seem like a recent invention，but they've been around for years.In the early 1900s，there were more electric cars on the road than there were petrol （汽油） cars.At that time，petrol was （1）e

xpensive

xpensive

compared with other fuels （燃料）. （2）W

hen

hen

petrol prices dropped and new technologies were developed，electric cars went out of fashion （過時）.Instead，petrol cars became more（3）p

opular

opular

because they could travel longer distances （距離） without stopping.
   During the 20th century，petrol cars got bigger，heavier，and faster.They needed more fuel，and it（4）c

aused

aused

more air pollution.For years，car makers didn't worry about pollution.They didn't worry about the amount of petrol cars used， （5）e

ither

ither

.But when people began to realise that there was not enough oil on the earth，they asked car makers to produce more efficient （高效能的） and less polluting cars.
   One （6）m

ethod

ethod

of solving the problem was a "hybrid" car （混合動力車），one that ran partly on petrol and partly on electricity.Hybrid cars became popular in the 2000s when petrol prices went up and the prices of hybrid cars went（7）d

own

own

.
   An all-electric car uses no petrol.The problem，however，is that car batteries （電池） need to be recharged （再充電）.That makes electric cars not so useful for long （8）j

ourneys

ourneys

.
   Many people are not （9）p

leased

leased

with it.The government and car makers are（10）w

orking

orking

together to develop safe，cheap，and useful electric cars.When people have these cars in the future，a petrol station may be a thing of the past.