9. By the time they invited me to travel to Los Angeles with them, I had planed my trip to England.

→ By the time + S1 + V1(ed/PI), S2 + had + V(ed/PII) → dùng để nhấn mạnh một hành động xảy ra trước 1 hành động khác trong quá khứ.

10. Many educational posters were displayed on the street by the local government to encourage people to protect the environment.

→ Câu bị động của thì quá khứ đơn: S + was/were + P2

`9`.By the time they invited me to travel to Los Angeles with them , I had planned my trip to England

`\rightarrow` Cấu trúc : By the time + S + Ved / V2 , S + had + V3 / PII

`10`.Many educational posters were displayed on the street to encourage people to protect the enviroment by the local government

`\rightarrow` Câu bị động `-` Thì QKĐ : S + was / were + V3 / PII ( by O )

`\text{@ TheFox}`