Rewrite these sentences as directed in the brackets 
3.We make the air dirty because we use the car all the time.(If)
4.Although the ticket price was high,many people went to see that film.(However)
11 Minh hopes to speak english well in 3 years.-Minh hopes that                                                                                                 
12.Our sources of energy will soon end if we don't try to save them.-Unless