Listening to loud music at rock concerts ______caused hearing loss in some teenagers.

A large number of people ______present at the meeting yesterday afternoon.  

Here _____a set of keys.The keys _____Bob’s.

______ Kitty ______ Cathy is going with you because one of them must stay at home.

The government’s efforts to cut the homework burden of primary and middle school students _____ mixed reactions(反应).