Answering the door B1
Someone's at the door — letting folk in, keeping the cat from getting out.
Let people in and out
let in — allow entryA: Who's at the door?
B: It's just Sarah. Can you let her in?
let out — allow someone to leave a placeA: The meeting's over. Can someone let me out?
B: Sure, I'll open the door for you.
keep out — prevent entryA: Why is there tape across the door?
B: They're painting inside, so they're keeping everyone out until it's dry.
That'll be the plumber
Beth: That's the bell — can you let him in? It'll be the plumber.
Gary: On it. Mind the cat doesn't shoot out the door.
Beth: Yeah, keep her out of the hallway, she'll bolt.
Gary: Too late, she's gone. I'll let her out the back later.
Locked out
Nadia: I've left my keys inside. Can you buzz and let me in?
Tom: Course. The door sticks, give it a shove.
Nadia: Ta. We really ought to fix that latch, it won't keep anyone out as it is.
Tom: Tell me about it. I'll have a look at the weekend.