Mark is the man, who donated his house for the homeless.

[keannu]

My gammar book says only 1 is possible without any context, but wouldn't 2 be also possible with further context?

gz46
1. Mark is the man who donated his house for the homeless.
2. Mark is the man, who donated his house for the homeless.

I know a man who is very generous. Mark is the man, who donated his house for the homeless.

[emsr2d2]

From the questions you've asked recently keannu, the author of your grammar book appears to know what s/he is talking about

Edit: as per 5jj's post further down, this wasn't actually my original post. It's 5jj's. Sadly, (or perhaps luckily for the rest of you) I have no recollection of what I originally wrote except it was something to do with using "He's the man!" meaning "He's the best!"

[keannu]

So can I ignore the author's intention? Maybe it all depends on context.
Basically,restricitve clause like 1 is for identifying the antecedent while non-restrictive clause like 2 is for extra information of the antecedent.

In 2, if "the" appears without any previous context referring to "the", does it sound awkward?
2. Mark is the man, who donated his house for the homeless.

[5jj]

From the questions you've asked recently keannu, the author of your grammar book appears to know what s/he is talking about

Sorry about that, ems. Instead of responding to a post, I accidentally edited your post - and replaced it with mine.

[keannu]

Anyways, I need my answer, please!

[emsr2d2]

5jj's post answered your question - the person who wrote your grammar book knows what they are talking about.