She (may/ couldn't) join us for dinner tonight. She hasn't decided yet.
may
He (might/ may) be at the library now, but he usually studies at his apartment.
might
We (could/ couldn't) see a movie later. It depends on how much work we finish.
could
He (might not/ could not) be at the library now. He mentioned he had a meeting.
might not
They (may not/ could not) arrive on time. There's heavy traffic on their route.
may not
This project (might not/ could not) meet the deadline. The team is working hard, but there have been some delays.
might not
The solution (could/ could not) be simpler than we think. We haven't explored all options yet.
could
The weather (might/ could) improve by the afternoon. The forecast is uncertain.
might
This project (could/ might) turn out to be a success. The team has been working hard, but the market is unpredictable.
might
There (may not/ could not) be another chance to travel this year. It all depends on how work schedules align.
may not
