B1+ - U5 - Grammar

I couldn't find my keys and I thought I MIGHT HAVE lost them in the park.

They COULD HAVE joined us in Vietnam, but they decided to stay longer in Laos.

I SHOULD HAVE asked about the tickets. I think it's too late now.

He MUST HAVE done really well in the interview for them to offer him the job so quickly.

You NEEDN'T HAVE worried about giving the presentation. You were really good!

past possibility

past possibility

criticism of past actions

certainty about the past

lack of necessity or obligation in the past