The United States has one of the best highway systems in the world.
美国拥有世界上最好的公路系统u@vSi4yqwRDJl8]。
Interstate highways connect just about every large and mid-sized city in the country.
州际公路连接几乎所有大、中期的城市国家XpoJfy&dw+FzNNFx。
Did you ever wonder why such a complete system of excellent roads exists?
你有没有想过为什么这样一个完整的系统优秀的道路存在吗?
For an answer, you would have to go back to the early 1920s.
要回答这个问题，你必须回到20世纪20年代初##)|X8eaSwfw.e。
In those years, just after World War I, the military wanted to build an American highway system for national defense.
那些年,第一次世界大战之后,美国军方想建立一个国防公路系统wzIXU^o%rRi~r。
Such a system could, if necessary, move troops quickly from one area to another.
这样一个系统,如果必要,将部队迅速从一个地区到另一个地方XM^I+e~3r-r~JNQf。
It could also get people out of cities in danger of being bombed.
它也可以让人们的城市被轰炸的危险H^RMruaP6Vg9~RaG。
So-called roads of national importance were designated, but they were mostly small country roads.
所谓国家重要性的道路被指定,但他们大多是小国家的道路6QfDfJQv[Lp4FzcF。
In 1944, Congress passed a bill to upgrade the system, but did not fund the plan right away.
1944年,国会通过一项法案来升级系统,但没有基金的计划)]j=FM=!4.0V1R。
In the 1950s, the plan began to become a reality.
20世纪50年代，这个计划开始成为现实Gr7N752Xyy.S!Q。
Over $25 billion was appropriated by Congress, and construction began on about 40,000 miles of new roads.
由国会拨款超过250亿美元,建设开始于大约40000英里的新道路+yV|fumB&Mo!B。
The idea was to connect the new system to existing expressways and freeways.
当时的想法是将新系统连接到现有的高速公路和高速公路iwvmIajIx2Jwh3HF(o)。
And though the system was built mostly to make car travel easier* defense was not forgotten.
虽然系统建于主要是为了使汽车旅行更容易防御不被遗忘up*_+4J|Ysm-=Msi^(2。
For instance, highway overpasses had to be high enough to allow trailers carrying military missiles to pass under them.
例如,高速公路立交桥必须高到足以让拖车运送军事导弹通过TW_1M^N4qH^A!F#96UpF。
By 1974, this system was mostly completed.
到1974年，这个系统基本完成T2%zMB6y)A78Xel%*!。
A few additional roads would come later.
之后还会有一些其他的道路wfU%BbF!Gn。
Quick and easy travel between all parts of the country was now possible.
现在可以在全国各地之间方便快捷地旅行了MMW.@dlrjgY;@1ff+@。

Questions 19 to 21 are based on the passage you have just heard.
请根据你刚刚听到的文章回答问题19至问题21%pP+ZnR*u3hi*x&C。
Question 19. What does the speaker say about the American highway system?
问题19：关于美国的高速公路系统，讲话者都说了些什么?
Question 20. What was the original purpose of building a highway system?
问题20：修建公路系统的最初目的是什么？
Question 21. When was the interstate highway system mostly completed?
问题21：州际公路系统于何时基本建成？