Relative clauses, can't solve an exercise.

braswiss off · Gast

Hi everyone,

At the moment I am learning the rules about relative clauses.
"more or less" I do understand but I can not solve the following exercise:

(Info: Bob's mum has lost her car keys)
a). Bob's mum who is a musician has lost her car keys.
b). Bob's mum, who is a musician, has lost her car keys.

(Info: My friend Jane moved to Canada)
a).My friend Jane whose husband is Canadian moved to Canada last week.
b).My friend Jane, whose husband is Canadian, moved to Canada last week.

a or b is right and WHY? Which rule can I apply?

Thank you very much, specially because I am learning english by myself.
Franz

gast05 · Gast

b is correct. You need commas because the relative clauses are non-defining clauses. They are not necessary to clearly understand the whole sentence.
Only if a relative clause is required for the comprehensive understanding of a sentence, commas are used. Non-defining rel. clauses contain additional information that could also be missing without the sentence becoming unclear.

If you own a grammar book refer to this chapter for further examples and information.

Braswiss off · Gast

gast05 · Gast

Correction:

Only if a relative clause is required for the comprehensive understanding of a sentence, commas are not used.