单元同步完形填空训练

In the United States, children start school when they are five years old. In some states they must stay in school 1 they are sixteen. Most students are seventeen or eighteen years old when they 2 middle school. There are two kinds of schools in the US： public schools and private schools. 3 children go to public schools. Their parents do not have 4 their education because the schools 5 money from the government.