( )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