Trạng từ quan hệ có thể được sử dụng thay cho một đại từ quan hệ và giới từ. Cách làm này sẽ làm cho câu dễ hiểu hơn.

Ví dụ: This is the shop in which I bought my bike.

=>  This is the shop where I bought my bike.

Trạng từ quan hệ	Tương đương	Cách sử dụng	Ví dụ
when	in/on which	Đại diện cho cụm thời gian	the day when we met him
where	in/at which	Đại diện cho nơi chốn	the place where we met him
why	for which	Đại diện cho lí do	the reason why we met him

1. WHY

Trạng từ quan hệ why mở đầu cho mệnh đề quan hệ chỉ lý do, thường thay cho cụm for the reason, for that reason.

Ví dụ 1: I don’t know the reason. You didn’t go to school for that reason.

=>  I don’t know the reason why you didn’t go to school.

Ví dụ 2: I don't know the reason. You didn't go to school for that reason.

 => I don't know the reason why you didn't go to school.

 

2. WHERE

Trạng từ quan hệ để thay thế cho các từ/cụm từ chỉ địa điểm, nơi chốn.

Ví dụ 1: The hotel wasn’t very clean. We stayed at that hotel.

=> The hotel where we stayed wasn’t very clean.

Ví dụ 2: This is my hometown. I was born and grew up here.

=> This is my hometown where I was born and grew up.

 

3. WHEN

Là trạng từ quan hệ để thay thế cho cụm từ/từ chỉ thời gian.

Ví dụ 1: Do you still remember the day? We first met on that day.

=>  Do you still remember the day when we first met?

=>   Do you still remember the day on which we first met?

Ví dụ 2: I don’t know the time. She will come back then.

=>  I don’t know the time when she will come back.

Ví dụ 3:That was the day. I met my wife on this day.

=> That was the day when I met my wife.