Spotting Your Opponent's Mating Threat

Your opponent is threatening to win in 1 move and it's up to you to spot it so you can plan to stop it.

I'm going over these as it's crucial to see threats from your opponent's point of view. Rather than just looking at what your own pieces can do, make sure you keep an eye out for your opponent's plans as well. So in these positions it would be your turn, but the puzzle is you moving for your opponent to test if you can really see what your opponent is threatening.