Phân biệt sự khác nhau giữa First và Firstly

Cho mình hỏi các câu này làm sao ạ?

1.I think we shouldn't buy that car.

->Let's

2.I suggest those products shouldn't be bought.

->I suggest

3.Let's take these bottles to a recycling center.

->I suggest

4.How about replacing the broken window,

->I suggest the

5.Please don't leave the light on during the night.

->I suggest that

6.Flowers won't bloom if there isn't enough water.

->Unless flowers

7.If you don't succeed you will have to try it again.

->Unless you

8.The weather was really bad, so we decided to postpone our camping.

->Since

9.Even thought he had a car, he still bought a new one.

->He had

10.The boy drove carelessly,so he caused the accident.

->Since

11. Despite not feeling well he tired to finish the word.

->Even

12.They tired hard,but they couldn't win the match.

->Despite

13.He is humorous and generous, so we all love him.

->Because of

Trình bày suy nghĩ của em về hiện tượng vứt rác bừa bãi trong trường học khoảng 10 dòng( không lấy trên mạng nha😗) cảm ơn ạ.