Question

why does this relative clause have no commas

Passengers who have young children may board the aircraft first.

vs non-restrictive relative clause

Mary, who has two young children, has a part-time job in the library.

Accepted Answer

because it's a restrictive relative clause... the sentence would not make sense without itthe second sentence does make sense, so no commas are necessary

Front	why does this relative clause have no commas Passengers who have young children may board the aircraft first. vs non-restrictive relative clause Mary, who has two young children, has a part-time job in the library.
Back	because it's a restrictive relative clause... the sentence would not make sense without it the second sentence does make sense, so no commas are necessary

Relative Clause Commas Young Children Sentence Make Passengers