The mechanic checked the tyres on my car.                             had  

          The mechanic _____________________________________________________

4. It is necessary that I post this letter tonight.                       need 

          I _______________________________________________________________

5. I am interested in why you did it.                                        is      

          The only thing_____________________________________________________

6. You'll be ill if you continue to smoke.                                 stop  

          Unless___________________________________________________________

8. We spent three hours painting that door.                                     us     

          It took ___________________________________________________________

10. I've never eaten this food before .                                               time  

          This_____________________________________________________________