What are you going to do this Saturday ?----- I ______ yet .
The actors __________ in the movie.
—How many birds can you see in the trees? —I can see _________ birds in them.
—Where is Miss Wang? —She went to Hainan Island last week and will return _______ six days.
There will be _________ pollution this year than last year.
—Will people live to be 300 years old? —_________.