In Verbs^x, Negations^x, Conversations^x

I am trying to formulate guidelines for learners of English as a foreign language with regards the use of may/might/could to express possibility. It seems to me that you can use these three modals (almost) interchangeably when expressing possibility. For example, 'Where's Mary?' 'I'm not...

CalifJim wrote: I don't think there really is a "right context" for this sentence. It seems somehow ill-formed. The problem is the ambiguity in the scope of the negation. Tom hasn't been sleeping since 2. "Tom has been doing non-sleeping since 2"? i.e., Tom has been (continuously) awake since 2....

I don't think there really is a "right context" for this sentence. It seems somehow ill-formed. The problem is the ambiguity in the scope of the negation. Tom hasn't been sleeping since 2. "Tom has been doing non-sleeping since 2"? i.e., Tom has been (continuously) awake since 2. OR...

Thanks, I didn't know this was called "transferred negation", that's a good pointer in Google According to Section 6 in this doc: http://www.lancs.ac.uk/postgrad/xiaoz/papers/negation%20in%20english.doc , the "I don't think X" formulation has a slighly different use, as the strength of the...