第二部分：单项填空(共15小题；每小题1分，满分15分)
21．-When will the bus leave ？
    -It        very soon．
    A．is leaving      B．1eaves      C．would leave   D．1eft
22．Do you know the boy        under the big tree?
   A．lay       B．lain       C．laying    D．lying
23．The number of people invited     fifty，but a few of them      absent for different reasons
    A．were; was     B．Was；was      C．was；were     D．were；were