A、Every ten minutes. B、Every half hour, C、At twenty to one. D、Once a day. B

M: Excuse me. Have you been waiting long?
W: About ten minutes.
M: Did you notice whether the number seven bus has gone by?
W: Not while I’ve been standing here. I’m waiting for the number seven myself.
M: Good. Hot day today, isn’t it?
W: Yes, it is. I wish that it would rain and cool off.
M: Me too. This is unusual for March. I don’t remember it has ever been so hot and dry in March before.
W: You’re from Florida then?
M: Not really. I was born in New York, but I’ve lived here for ten years now.
W: My mother and I have moved here from Indiana.
M: Pretty cold in Indiana, isn’t it?
W: Yes. That’s why we moved. But we didn’t know that it would be so hot here. We should have gone to California. Do you think that we’ve missed the bus?
M: No. It’s always a little late.
W: I have twenty to one, but my watch is a little fast.
M: Don’t worry. It never comes exactly on the half-hour like it should.