---How did it _________ that all the flowers died ? ---I had forgotten to water them.
They are demanded to finish their task __________.
I thought the medicine would make him sleep, but it had the __________ effect.
__________ the growing number of patients, the clinic had to extend its service from five days to seven days a week.
The owner of the shop asked his assistant to__________ the pears that can be thrown away.
Many people __________ the opening ceremony of the 2010 World Expo, which was so amazing.