The bicycle is one of the simplest yet most useful inventions in the world. What is most surprising is that it was not ___1__ earlier, although the great inventor Leonardo Da Vinci had drawn pictures for bicycles and also for flying machines and some other things. Those things were not produced___2___ long after he died.
　　A person riding a bicycle uses ___3___ energy to make the bicycle move, and there is no pollution at all when you are riding. Even so, in developed ____4___, most people don’t travel to work by bicycle. It is not because the bicycles are expensive or people feel___5____ if they ride to work. It’s because __6___ cars on the roads becomes larger. It certainly becomes ___7___ to ride a bicycle. As a result, more people put their bicycles away and go to work ___8___ their cars , and in this way, the situation is made more serious.___9___ the best way to make riding safer and more popular is to create paths (开设通道) only for bicycles, and to make ___10___ so difficult and expensive for drivers to take their cars into the city that they will go back to use their bicycles.

A．invent B．inventing C．invented D．to invent

A．before B．when C．since D．until

A．much B．quite a lot of C．very little D．many

A．world B．countries C．land D．earth

A．lucky B．glad C．sorry D．tired

A．the number of B．a number of C．this kind of D．all kinds of

A．safer B．more dangerous C．much dangerous D．safe

A．by B．in C．use D．drive

A．Hardly B．May be C．Perhaps D．Nearly

A．it B．them C．us D．that