Tom, clean up the broken glass _________ someone walks on it.
One of the best ways for people to keep fit is to ______ healthy eating habits.
The building around the corner caught fire last night. The police are now ______ the matter.
A survey was carried out on the sleep time of students in middle schools, ______ were surprising.
---Do you have ______ for the party, Mary? ---No, we still have to get another five chairs and some fresh flowers.
Was it in 1969______ the American astronaut succeeded ______ landing on the moon?