1. Many new bridges have been built (built) since 2010.  

2. Our classroom has been cleaned (clean); you needn’t clean it now.  

3. All possible means have been tried (try), but nothing can prevent the buildings from being pulled down.  

4. Many a new measure has been put (put) forward to reduce air pollution so far.  

5. The construction of the two railway lines has been completed (complete) by now.  

6. —Why do you look so worried?

—My computer broke down and my essay has been left (leave) unfinished since.  

7. For a long time we have been told (tell) that going to university and getting a degree will ensure a financially stable future.  

8. Up to now, large quantities of food have been sent (send) to Africa to save the starving people.