`16,` We went to Ho Chi Minh City where my grandmother used to live.

`17,` `2000` was the year when I graduated from high school.

`18,` We love Sundays when we don't have to go to school.

`19,` It is wonderful to visit Japan in April when the cherry trees are blooming.

`20,` It was midnight when the fire broke out.

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Giải thích: 

`-` when để thay thế cho các từ chỉ thời gian. 

`->` N (tgian) `+` when `+` S `+ `V

`-` where để thay thế N chỉ nơi chốn.

`->` N (địa điểm) `+` where `+` S `+` V.. (where = on/in/at + which)

Đáp án `+` Giải thích các bước giải:

`\star` When 

`+` Dùng để thay thế các danh từ chỉ thời gian

`+` .... N(thời gian) when + S + V + ...

`\star` Where

`-` Thường dùng để thay thế cho từ 'there'

`+` Dùng để thay thế các danh từ chỉ địa điểm

`+` ....N(địa điểm) where + S + V + ...

`--------------`

`16.` We went to Ho Chi Minh City where my grandmother used to live.

`17.` `2000` was the year when I graduated from high school.

`18.` We love Sundays when we don't have to go to school.

`19.` It is wonderful to visit Japan in April when the cherry trees are blooming.

`20.` It was midnigh when the fire broke out.

`----------------`

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$\color{orange}{\text{Chúc bạn học tốt ạ :33}}$