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