close/shut...any difference?

[snickchap]

Hi,
I had a student ask me the other day about the difference between the two verbs 'to close' and 'to shut'. I found this quiz to help him out http://www.english-test.net/esl/lear...0/esl-test.php , but I haven't been able to give him a clear, concise explanation (if there is one).
Any ideas on how to explain the difference between 'to close' and 'to shut'? Is there any clear explanation for 'close/shut' like there is for the verbs 'to come' and 'to go'?

Any help would be appreciated.
Sincerely,
S.

[Mister Micawber]

.
Apart from the idiomatic or highly collocated uses, as appear in several of those quiz questions (open-and-shut case; the road is closed, etc), I see no difference except a slight one of formality, close being preferred in writing, perhaps.
.