16. I returned home with some roses and only then __________ find my favorite vase missing.
Judging from his______ expression, this problem must be quite ______.
Listen! Do you hear someone _____ for help?
--How is your cousin, Kate? --She broke her leg and ______ medical treatment since.
--Mom, may I play computer games just for a while? --______! Dad is writing his paper.
It took ______ building supplies to construct these energy saving houses. It took brains, too.