16. People believed (that) science and technology were the keys to develop the country.

→ S1 + believed (that) + S2 + V(lùi thì) 

17. Our teacher said (that) we had to wear uniform next Monday.

→ S1 + said (that) + S2 + V(lùi thì) 

18. The boy said that he had seen the alien the day before when he had been going out with his friends.

19. My friend told me (that) he had just received a birthday gift from his mother.

→ S1 + told + O (that)  + S2 + V(lùi thì) 

20. She said the story about that had happened long before

Bạn học tốt ~

# Yumi

16. People believed that science and technology were the keys to develope the country

17. Our teacher said we had to wear uniform the next Monday

18. The boy said that he had seen the alien the day before when he had been going out with his friends

19. My friend told me he had just received a birthday gift from his mother

20. She said the story about that had happened long before