1. Boiling an egg is not difficult
-> It
2. The ancient Egyptians built the pyramids
-> The pyramids
3. Cairo is hotter than Lon don
-> Lon don isn't
4. It's two years since I was just in Ha noi
-> I have not
5. She is overweight because she eats too much meat
-> If she
6. '' I have visited this beauty spot many times '' said my father
-> My father told me
7. People say that he is a famous singer
-> It
8. The police man does not run so fast as the thief
-> The thief
9. I haven't seen this man here before
-> This
10. The novel is very interesting
-> We
11. Please don't smoke in the dining room
-> I'd rather
12. The flight to Moscow lasted three and a half hour
-> It took
13. Mrs. Smith is the wisest member of the family
-> No member
14. I remembered and so did she
-> He didn't
15. I wasn't there at that time
-> He denied