Help the amateur detective piece together the mystery of the missing chocolate cake. Choose the correct modal verb for each gap to complete her notes.

I left the cake on the counter, and now it's completely gone! Someone must have taken it while I was outside watering the plants.

It couldn't have been my little brother, because he is currently at a summer camp in another state.

The dog might have eaten it, but he looks completely innocent right now, and there's no frosting on his nose.

Someone must have taken it while I was outside watering the plants.

We use must have + past participle when we are almost certain that something happened in the past based on the evidence (the cake is gone).

It couldn't have been my little brother, because he is currently at a summer camp in another state.

We use couldn't have or can't have + past participle when we are almost certain that something did NOT happen in the past (it's physically impossible since he is out of state).

The dog might have eaten it, but he looks completely innocent right now.

We use might have + past participle when we think it is possible that something happened, but we aren't completely sure.