Past modals - degrees of certainty, judgments, suggestions
Yumiko: Yoko still hasn't called me back. Tanaka: She ___ gotten your message. (it's not possible)
may/might not have gotten
Emily: "I can't believe we missed our flight to Paris!" Alex: "I know, it's my fault. I ____ checked the departure time."
should have
Lisa: "I lost my wallet, and now I can't find it anywhere!" David: "You ____ left it at the restaurant when we had lunch."
may/might have