`1.` She is not used to driving on the left.

`->` be used to doing sth: quen với việc làm gì

`2.` Breakfast is served by the waitress at 7 o'clock.

`->` Bị động thì HTĐ: S + am/is/are + P2 + (by O)

`3.` Due to the extremely severe weather, they didn't find the trip interesting.

`->` Due to + Noun/Noun Phr/V-ing, clause: bởi vì...nên...

`4.` The boy who was six years old brought a gun to school in March.

`->` who là đại từ quan hệ dùng làm tân ngữ/chủ ngữ thay thế cho danh từ chỉ người

$\color{#00FFFF}{\text{#}}$$\color{#CCFF99}{\text{ᗩ}}$$\color{#99FF99}{\text{ꮮ}}$$\color{#33FF99}{\text{ꮖ}}$$\color{#00FF99}{\text{ꮑ}}$$\color{#99FFCC}{\text{ꭺ}}$$\color{#66FFCC}{\text{ꭺ}}$$\color{#00FF33}{\text{ꭺ}}$$\color{#00FFCC}{\text{ꭺ}}$$\color{#00FFFF}{\text{ꭺ}}$⭐

$1$. She is not used to driving on the left.

`***` used to do sth (v): từng làm điều gì đó..

$2$. Breakfast is served by the waitress at 7 o'clock.

`@` Bị Động HTĐ:

$-$ S $+$ am/is/are $+$ V ed/PTII by sb

$3$. Due to the extremely severe weather, they didn't find the trip interesting.

`***` Due to $=$ Because : Bởi vì

`***` severe (a): kinh khủng

$4$. The boy who brought a gun to school in March is 6 years old

`@` QKĐ:

$-$ S $+$ Ved/ cột 2