The police officer has just arrested a man. He robbed the bank.

• The police officer has just arrested a man who robbed the bank. (Defining)

These are the shoes. I bought them in HCMC.

• These are the shoes that I bought in HCMC. (Defining)
• These shoes, which I bought in HCMC, are very comfortable. (Non-defining)

I want to know the reason. You didn’t go to work this morning for that reason.

• I want to know the reason why you didn’t go to work this morning. (Defining)

This is Jane’s new house. We celebrated her wedding anniversary here.

• This is Jane’s new house where we celebrated her wedding anniversary. (Defining)
• This is Jane’s new house, where we celebrated her wedding anniversary. (Non-defining)

We often go on holidays in the summer. We are given some days off.

• We often go on holidays in the summer when we are given some days off. (Defining)

Mothers will never forget the day. Their children are born on that day.

• Mothers will never forget the day when their children are born. (Defining)

Do you remember the restaurant? We held Mom’s birthday there.

• Do you remember the restaurant where we held Mom’s birthday? (Defining)

She remembers the day. She first met him on that day.

• She remembers the day when she first met him. (Defining)

I understand the reason. You called off your wedding for that reason.

• I understand the reason why you called off your wedding. (Defining)

Astronomers will never forget this day. They found a new constellation that day.

• Astronomers will never forget the day when they found a new constellation. (Defining)

The children often go for picnics on Sundays. They have a lot of free time then.

• The children often go for picnics on Sundays when they have a lot of free time. (Defining)

He doesn’t know the reason. You didn’t go to the party last night for that reason.

• He doesn’t know the reason why you didn’t go to the party last night. (Defining)

Do you remember the place? We went on holiday there last year.

• Do you remember the place where we went on holiday last year? (Defining)

This is the house. Many paranormal events happened there.

• This is the house where many paranormal events happened. (Defining)

It was John’s birthday. He proposed to Mary on that day.

• It was John’s birthday when he proposed to Mary. (Defining)

Do you remember the house? We used to live there for 3 years.

• Do you remember the house where we used to live for 3 years? (Defining)