1. He didn't go to school because he had to stay at home to to look after his sick mother.

→ S+V + because + S +V +O
2. We got to the main island after travelling three hours by boat.

→ Got to: đã đến.

→ Sau after + V-ing 

$@AlinaUyn$

`35.` He didn't go to school because he had to stay at home to look after his sick mother.

`->` because + mệnh đề nguyên nhân

`->` thì QKĐ:
`(+)` S + Ved/V2

`(-)` S + didn't + V-bare

`->` have to do sth: phải làm gì

`36.` We got to the main island after three hours travelling by boat.

`->` by + phương tiện

`->` after `+` time `+` V-ing: sau bao lâu làm gì

`->` get to `+` place: đi đến đâu đó