Ⅰ.单项选择(每小题1分，共15分)
1．It ______sunny today，but it ______ cloudy yesterday.
A．is；is B．was；was
C．is；was D．was；is
2．I ______ at school now，but I ______ at home an hour ago.
A．am；am B．was；was
C．am；were D．am；was
3．—______ there any students in the classroom?
—No，there aren't.But there ______ some half an hour ago.
A．Are；were B．Were；are
C．Are；are D．Were；were
4．—Where ______ you last night?
—I ______ at home.
A．are；am B．am；am
C．were；was D．were；were
