1. I have a friend. Her mum is a volunteer worker.

......I have a friend whose mum is a volunteer worker.........

2. It is a camping shop. It has a lot of good equipment.

........It is a camping shop which has a lot of good equipments.......

3. The rescue operation was arranged by a charity organization. It was a success 

........The rescue operation which was arranged by a charity organization was successful.......

4. My uncle is a fire fighter. He visited us last weekend 

.........My uncle visited us last weekend who is a firefighter........

5. 2015 is the year. Mr sisters became a nurse 

....My sister became a nurse in 2015............

6. The storm started at 2 o'clock this morning. It caused a lot of damage 

.........The storm which caused a lot of damage started at 2 o’clock this morning.........

7. Nick is my classmate. I've known him for a long time 

....I've known Nick for a long time who is my classmate...............

1. I have a friend. Her mum is a volunteer worker. 

→→ I have a friend whose mum is a volunteer worker.

2. It is a camping shop. It has a lot of good equipment.

→→ It is a camping shop which has a lot of good equipments.

3. The rescue operation was arranged by a charity organization. It was a success.

→→ The rescue operation which was arranged by a charity organization was successful.

⇒⇒ Dùng which cho rescue operation để nối lại câu

4. My uncle is a firefighter. He visited us last weekend.

→→ My uncle visited us last weekend who is a firefighter.

⇒⇒ Vì có is nên dùng who.

5. 2015 is the year. My sister became a nurse.

→→ My sister became a nurse in 2015

6. The storm started at 2 o’clock this morning. It caused a lot of damage.

→→ The storm which caused a lot of damage started at 2 o’clock this morning.

⇒⇒ Để chỉ cơn bão thì dùng which.

7. Nick is my classmate. I’ve known him for a long time.

→→ I've known Nick for a long time who is my classmate.