`39`. I haven't spoken to her for two years.

- It's + thời gian + since + S + last + V2/ed

= S + have/has + not + Vpp + for + khoảng thời gian

`40`. It is interesting to go swimming in the river in the summer.

- It + be + adj + (for SO) + to V

= N/Ving + be + adj (Ving đứng đầu câu làm chủ ngữ thì V chia số ít)

`41` Because it rained heavily, we were late for school.

- Because + S + V = Because of + N/Ving: bởi vì

`42`. We used to be made to clean the house by my mother.

- Bị động với "used to": S + used to + be + Vpp

`39`.I haven't spoken to her for two years

`\rightarrow` Thì HTHT : S + haven't / hasn't + VpII

`\rightarrow` For + Khoảng thời gian : Bao lâu

`40`.It is interesting to go swimming in the river in the summer 

`\rightarrow` It is ( not ) + adj ( for O ) + to do sth : Như thế nào để làm gì

`41`.Because it rained heavily , we were late for school

`\rightarrow` Because + C1 + C2 : Bởi vì

`=>` Dùng để chỉ nguyên nhân , lý do

`42`.We used to be made to clean the house by my mother

`\rightarrow` BĐ `-` used to : S + used to be + VpII ( by O )

`\rightarrow` be made + to do sth : Bị bắt làm gì

`\text{# Eternal}`