As the quality of the city’s air continues to give rise to ______, the residents are encouraged to set off fewer fireworks. 

I used to go to the gym three times a week, but I don’t _______ any more.

Michelle found a job as a high school teacher which _____ spending quite a lot of time with students.

—How much did the guy ________ you to fix your 3G mobile phone?—I don’t remember，but it was quite a lot.

My hometown has changed so much that I can't ________ it.