could or might/may

[bosun]

In the following sentence, can I use ' could' or migh/may to indicate possibility?

A.Where is the spatula? It should be in this drawer but it is not here.
I just did a load of dishes last n ight and they are still in the dish washer. It B. musst be in there. That's the only place it ________ be.

 

[Rover_KE]

In this sentence could is correct.

Rover

 

[bosun]

why can't I use ' might' or ' may' which indicate possibility like could?

 

[Raymott]

why can't I use ' might' or ' may' which indicate possibility like could?

Because they don't indicate possibility like 'could'. They indicate possibility in different ways which aren't appropriate in this context.

A: Where's the spatula?
B: The cat might have swallowed it.
A: The cat couldn't have swallowed it! Right.
A: * The cat mightn't have swallowed it. Wrong.

Some of the uses and the differences between the modals are subtle, and the only way to master them is with practice and use - ie. reading and listening.

 

[Rover_KE]

If it must be in the only place they haven't yet looked, then it's a certainty, not a possibility.

Rover

 

[gulesin]

Because they don't indicate possibility like 'could'. They indicate possibility in different ways which aren't appropriate in this context.

Could you explain these different ways more detailed please?

 

[Raymott]

Could you explain these different ways more detailed please?

No I can't. See my amended message above. When I say "different ways", I don't mean there are X different ways that can be explained didactically. I simply mean that they are used differently.
If you have a specific question, that is answerable. Otherwise a grammar book is the place to start, and a lot of reading is the next step.

 

[emsr2d2]

If you can't remember where you put the spatula, then there are a lot of places it might be. (There are alternative places where it might be.)

However, if you specifically remember putting it in the dishwasher, then that is the only place it could be. (There are no alternative places it could be.)

 

[bosun]

Then, what does this ' could' mean? I was told when we talk about possibility, might /may and could be used interchangeably and could indicates the weakest possibility. I am very confused.

 

[5jj]

Then, what does this ' could' mean? I was told when we talk about possibility, might /may and could be used interchangeably and could indicates the weakest possibility. I am very confused.

emsr2d2, Raymott and Rover have done the best that can be done without, as Raymott suggested, a lot of reading and listening. Read through their posts again, carefully.

'Could' in your sentence, means something like:

That is the only place in which there is a real possibility of its being. This possibility is so real that it is effectively a certainty.

 

[Raymott]

Then, what does this ' could' mean? I was told when we talk about possibility, might /may and could be used interchangeably and could indicates the weakest possibility. I am very confused.

It's probably worth pointing out that what you have been told is wrong.
Might/may/could are not used interchangeably. You will feel less confused once you accept this.
They do not indicate different levels of probability in standard English. If your spatula could be in the dishwasher, it is no more or less likely to be there than if it might be in the dishwasher.