`1.` Because it rained heavily, they led their trip .

`@` Because of + N/V_ing, S + V + O

`<=>` Because + S + V + O, S + V + O

`->` bởi vì `-` nguyên nhân

`2.` I think we should collect unused books for poor children.

`@` What/how about + V_ing + O?

`<=>` I think + you/we + should + V_inf + O

`->` gợi ý ai làm gì

-> Because it rained heavily, they led their trip

- Because of + N, S + V + O: Bởi vì việc gì

- Because + S + V, S + V + O: Bởi vì

2. I think we should collect unused books for poor children

- How about + V - ing?: Gợi ý làm gì

- S + think(s) + S2 + should + V - inf: Nghĩ ai đó nên làm gì