阅读理解 In the United States today, a large group of people want a college education. However, everyone is not able to attend a four-year college. Many four-year colleges are already too crowed. To give more people a chance to get a college education, some cities and towns have built junior colleges.
The junior college offers a two-year courses of study in a wide range of subjects. It prepares some young people to go on to a four-year college. It trains others for jobs in business, government, or industry.
Because junior colleges are built in cities, they can serve many people who live in a large community. Many students can not afford to go to a four-year college. But they can save enough to go to a junior college. The entrance fee at a junior college is low. Students can also save money by living at home.
A junior college admits some high school graduates who would not be accepted at other schools.
The four-year college turns down students whose high school grades are low. The junior college will often admit a student who might do well in taking a two-year course.
One of the goals of our country is to educate as many people as possible. The junior college is a school meant to serve many people. It puts a college education within the reach of a great number of people. Without these schools, many people would not be able to continue their education after high school.

单选题 18.The main idea of paragraph one is that junior colleges______.

单选题 19.According to the passage, junior colleges______.

单选题 20.It is known the passage that______.