Using "could" making a question

＊ It could rain tomorrow.

What is the question and negative sentences of the above sentence?

＊ question sentence: Could it rain tomorrow?

＊ negative sentence: It couldn't rain tomorrow.

Are they really the question and negative sentences of " It could rain tomorrow."?

Thank you for your help!

 The negative would normally be expressed by "It couldn't possibly rain tomorrow." (we're in the desert!)  or "It's not possible that it will rain tomorrow." (we've had rain for 40 days and 40 nights, and it's ludicrous to add on another day of rain!)  or by the opinion, "I don't think it will rain tomorrow."

 So, the sentence, "It could rain tomorrow." means "It is possible that it will rain."

Therefore, the question, "Is it possible for it to rain tomorrow?" and the negative, "It is not possible that it will rain tomorrow." are not so common, and therefore, sound odd.

V.C. 

As I can see the verb "could" is being used  when the possibility of event is hardly probable (comparing with may/might) and this is reffered to the present and future. Of course it isn't just one possibility of using that.  Am I right?

Teo

What about the acceptability of the following sentences?

1. May it rain tomorrow?

2. Might it rain tomorrow?

3. Can it rain tomorrow?

4. It may not rain tomorrow.

5. It might not rain tomorrow.

6. It cannot rain tomorrow.

2. acceptable.

3. acceptable.

4. acceptable.

5. acceptable.

6. acceptable. 

CJ