11. Ann was nvited to the party by Lan yesterday.
12. A lot of mistakes were made in the examination by her.
13. The door has been locked.
14. Football is played all over the world.
15. Rice was exported to many countries in the world.
16. A ruler is often be used to draw a straight line by students.
17. Letters are written to our friends twice a month.
18. When was that museum built ?
19. Students were given a lot of homework by teachers last term.
20. Smoking is banned in this restaurant.