�、�.完形填空。

　　The bicycle is one of the simplest yet most useful inventions in the world.What is the most surprising is that it was not __11__ 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 __12__ long after he died.

　　A person riding a bicycle uses __13__ energy (能源) to make the bicycle move，and there is no pollution at all when you are riding.Even so，in developed __14__，most people don't travel or work by bicycle.It is not because the bicycles are expensive or people feel __15__ if they ride to work.It's because __16__ cars on the roads becomes larger.It certainly becomes __17__ to ride a bicycle.As a result，more people put their bicycles away and go to work __18__ their cars，and in this way，the situation is made more serious.__19__ the best way to make riding safer and more popular is to create paths (開設通道) only for bicycles，and to make __20__ so difficult and expensive for drivers to take their cars into the city that they will go back to use their bicycles.

　　(C)11.A.invent B.inventing C.invented D.to invent

　　(D)12.A.before B.when C.since D.until

　　(C)13.A.much B.quite a lot of

　　C.very little D.many

　　(B)14.A.world B.countries C.land D.earth

　　(D)15.A.lucky B.glad C.sorry D.tired

　　(A)16.A.the number of B.a number of

　　C.this kind of D.all kinds of

　　(B)17.A.safer B.more dangerous

　　C.much dangerous D.safe

　　(B)18.A.by B.in C.use D.drive

　　(C)19.A.Hardly B.May be C.Perhaps D.Nearly

　　(A)20.A.it B.them C.use D.that