move happy invent draw until dangerous build in
tired because country useful |
The bicycle is one of the simplest but （1）
the most useful
the most useful
inventions in the world.What is the most surprising is that it was not （2）
invented
invented
earlier，although the great inventor Leonardo da Vinci had （3）
drawn
drawn
pictures for bicycles and flying machines and some other things.Those things were not produced （4）
until
until
long after he died.
A person riding a bicycle uses very little energy to make the bicycle （5）
move
move
，and there is no pollution at all when he is riding.Even so，in most developed （6）
countries
countries
，most people don't go to work by bicycle.It is not because bicycles are expensive or people feel （7）
tired
tired
if they ride to work.It's because the number of cars on the roads becomes larger.It certainly becomes more （8）
dangerous
dangerous
to ride a bicycle.As a result，more people put their bicycles away and go to work （9）
in
in
their cars.
And in this way，the situation is made more serious.Perhaps the best way to make riding safer and more popular is to （10）
build
build
roads only for bicycles.
