题目内容：

选词填空。（每个空格1分，共10分）

kind, many, for, have, until, expensive, they, student ,leave ,go

In the United States, children start school when they are five years old. In some states they must stay in school    61   they are sixteen. Most students are seventeen or eighteen years old when they   62  high school. There are two  63   of school in the United States: public school and private school. Most children go to public schools. Their parents do not have to pay  64   their education because the schools receive money from the government. If a child  65 to a private（私立的） school, his parents  66   to pay enough money for his schooling. Some parents still choose private schools, though they are much more  67  .

Today about half of the high school  68  go to universities after they finish the high school. A student at a state university does not have to pay too m  69  if his parents live in this state.

But many students work while they are studying at universities. In this way they can have good working habits and live by 70  own  habits .