Relative clauses - defining or non-defining?

1- I have three brothers.

My brother who lives in Sidney came to see me last month.

Without relative clause: My brother visited me last month.As I have more than one brother, I must define which brother I am talking about.

My brother, who lives in Sidney, came to see me last month.


2-I have one sister.

My sister who is 25 years old spent her holiday in France.

My sister, who is 25 years old, spent her holiday in France.

Without relative clause: My sister spent her holiday in France.As I only have one sister, I need not define which sister I am talking about.


3- Bob's mum has lost her keys.

Bob's mum who is a musician has lost her car keys.

Bob's mum, who is a musician, has lost her car keys.

Without relative clause: Bob's mum has lost her car keys.As usually everbody has only one mum, I need not define who exactly I am talking about.


4- My friend Jane moved to Canada.

My friend Jane whose husband is Canadian moved to Canada last week.

My friend Jane, whose husband is Canadian, moved to Canada last week.

Without relative clause: My friend Jane moved to Canada last week.The person is identified by her name, so I need not define who exactly I am talking about.


5- I am a shoe fanatic.

The shoes which I bought yesterday are very comfortable.

The shoes, which I bought yesterday, are very comfortable.


6- Mr Robinson is very famous.

Mr Robinson whom I met at the trade fair is a famous inventor.

Mr Robinson, whom I met at the trade fair, is a famous inventor.

Without relative clause: Mr Robinson is a famous inventor.The person is identified by his name, so I need not define who exactly I am talking about.


7- Tamara has two cats. Both of them are black.

Tamara's two cats which can play outside are black.

Tamara's two cats, which can play outside, are black.

Without relative clause: Tamara's two cats are black.As Tamara has only two cats, I need not define which cats I am talking about.


8- Kevin has four cats. Two of them are black.

Kevin's two cats which are black can play outside.

Without relative clause: Kevin's two cats can play outside.As Kevin has four cats, I must define which of the cats I am talking about.

Kevin's two cats, which are black, can play outside.


9-We are on holiday. Yesterday we visited a church.

The church which we visited yesterday is very old.

The church, which we visited yesterday, is very old.


10-We are on holiday. Yesterday we visited a church.

St. Mary's Church which we visited yesterday is very old.

St. Mary's Church, which we visited yesterday, is very old.

Without relative clause: St. Mary's Church is very old.The church is identified by its name, so I need not define which church I am talking about.