There is no greater pleasure than running on the playground, ____ after a ball.
A. chased B. chasing
C. to chase D. having chased
I have told you the truth. ______ I keep repeating it?
A. Must B. Can C. May D. Will
Their relationship_______ ups and downs over the past century.
A. will see B. sees
C. has seen D. had seen
________carefully if any change occurs when doing experiments in the lab.
A. Observe B. To observe
C. Observed D. Observing
______ before bed, cellphones can result in a restless night.
A. To use B. Using C. Used D. Having used
Love is_____ makes you smile when you are tired.
A. that B. what C. it D. which
