We’ll go to the park if it ________.

Every family in America has had this sort of experience     there was a price increase of nearly one-third in the past two years

Engines are to machines _________ hearts are to animals. 

You can arrive in Guangzhou on time for the fashion show ____ you don’t mind taking the night train. 

— Do you think when they           to play basketball with us?— I think they’ll come when they           free．