[texhax] question about handing sentences

[Roseray]

Dear everyone,

I am preparing my thesis using latex. I have have multiple "orphans" ("hanging words or sentences") at the tops of several pages. My thesis coordinator doesn't like that. He suggests me to fix them by either moving a sentence fragment to
the bottom of the previous page, or add an extra
line of text to the top of the next page to have at least two
lines of text. But I don't know how to do that. 
Who could help about that? 

Thanks,
Roseray