Examples. JACK: I keep wondering what Molly's doing now

JACK: I keep wondering what Molly's doing now. Just think! She could/ may/might be sitting in front of a beautiful fire. She could/may/ might he dancing in the arms of one of those handsome ski instructors.

Could also has the same meaning as may/might with the verbs be and have, even when they are not in the continuous form.

Examples

(YOLANDA's telephone is ringing.)

YOLANDA: Who could that be? It's so late.

JACK: It could/may/might be Molly.

(YOLANDA answers the phone.)

YOLANDA: Hi, Molly. How are you? Oh. no! Really?Your leg?

ARNOLD: Uh oh. It sounds like Molly hurt herself.

JACK: She could/may/might have a broken leg.

YOLANDA: Jack, come here and speak to Molly. It's nothing serious. She only sprained her ankle. She's coming home tomorrow.

We frequently use could in questions about possibility. It is not necessary to use «Do you think...?» The rules for short answers are the same as those for may/might and must.

Examples

Could Jack be jealous?

Yes, he could be. In fact, he probably is.

Could Jack be losing Molly?

He's afraid that he could be.

Could Molly be looking for another man?

She could be, but Yolanda doesn't think she is.

Impossibility – Present

When we are talking about possibility and use could not (couldn't), we mean that we think something is impossible. We also use cannot (can't) for this meaning.

Example

According to Yolanda, Molly couldn't/can't be thinking of breaking up with Jack. This is because Molly tells Yolanda everything, and she has never mentioned anything about that.

In affirmative sentences about the present moment, may/might and could have the same meaning. In negative sentences, the meaning of could not is different from the meaning of may not and might not.