A. LÝ THUYẾT

• Với các động từ đi kèm với giới từ, khi sử dụng mệnh đề quan hệ chúng ta sẽ đảo giới từ lên trước whom / Which

Ví dụ:

The man speaks English very well. I talked to him last night.

-> The man to whom I talked last night speaks English very well.

The house is for sale. I was born in it

-> The house in which I was born is for sale.

• Of which/ Of whom: thường sử dụng khi có các từ "all", "most"

Ví dụ:

Daisy has three brothers, All of them are teachers.

-> Daisy has three brothers, all of whom are teachers.

He asked me a lot of question. I couldn't answer most of them.

-> He asked me a lot of questions, most of which I couldn't answer.

Lưu ý: Không dùng that sau giới từ.

The house in that I was born is for sale.

• At which / in which: có ý nghĩa tương đương với "where". At which sử dụng cho các địa điểm nhỏ hơn làng (Ví dụ: Bookshop, Cinema,...), in which sử dụng cho các địa điểm lớn hơn làng (Ví dụ: Country, city,...)

Ví dụ:

I like the restaurant. Whe ate Indian food there last week.

-> I like the restaurant at which we ate Indian food last week. 

We have been to London. Our friend lives there.

-> We have been to London in which our friend lives.

• On which: có ý nghĩa tương đương với when.

Ví dụ:

My favourite season is summer. We go to the beach at that time.

-> My favourite season is summer on which we go to the beach. 

• For which: có ý nghĩa tương đương với why.

Ví dụ: 

Tell me the reason. You are late for that reason.

-> Tell me the reason for which you are late.