第 一节 单项选择（共15小题；每小题1分，满分15分）
21．The number of people who English as a foreign language more than 750 million.
A. learns; is B. learn; are C. learns; are D. learn; is
22．When you finish, please put the book back it was.
A. where B. at which C. the place D. the place that
23．____home, the light in the room was still on.
A. Arriving B. On arriving C. When arriving D. When I arrived
