Someone mentioned that "with children's books and DVDs equally second at 20% each" in the following sentence from another question is a verbless adverbial clause.
In 2005, fiction made up the largest proportion of items borrowed at 35% with children's books and DVDs equally second at 20% each.
Actually, I would like to ask if it is or it is not qualified as a verbless adverbial clause there, but I don't want to make that question lose its focus. (If you can clear that point here too, I will be grateful. To me, it looks like one.)
So I searched for the definition of verbless adverbial clause, and this link at About.com came up. I was surprised to see these examples there,
The following sentences contain further examples of verbless clauses (italicized):
(38) He considered the girl a good student.
(39) Whenever in trouble, Bill rang his girl-friend.
(40) He married her when a student at Harvard.
I've no problems with other examples but (40). The (40) sounds very odd. It was mentioned that the examples were taken from (Herman Wekker and Liliane M. V. Haegeman, A Modern Course in English Syntax. Taylor & Francis, 1985), and I could find its PDF at the Internet Archive, so I can confirm that the example (40) has no misspelling nor omissions.
Is the sentence "He married her when a student at Harvard," grammatically correct, according to today's English grammar?