1. I suggest our environment should be kept unpolluted.
2. The peach which was still green eaten by her.
4. Since (=because) they didn't have a map, they lost their way.
5. Unless you tell me the truth, I won't ever talk to you again.
6. The cook whom Tom told me about this morning is very good.
7. You should pride yourself on your listening skills.
proud of + N/V-ing
pride oneself on + N/V-ing
take pride in + N/V-ing
8. Children like Lunar New Year best of many joyful celebrations in our country.
12. Kate suggested that energy-saving bulbs should be used to save electricity.
13. If I were you, I would help her out with a £500 loan.
14. The books which are interesting usually borrowed from her school library.
16. Because the river is too dirty, we can't swim in.
18. I would rather you didn't come late.
would rather + S + V2/ed (QKĐ)
19. Children always look forward to lucky money at Tet.
20. It's suggested that we should wear masks at public places.