He made up his mind to devote his life _____ pollution ______happily．

______have you been learning to swim —-Half a year.

The old man lives in the __________ house __________, but he doesn’t feel __________.[ ]

This old custom has________ since the 18th century, and remains practically unchanged.

May I go to the movie with you- No, you can’t, _____you have a ticket. I have only one ticket.