Dialog 1 water under the bridge [ 済んだこと ]

Angela:Was that Skippy I saw you walking with?
Yukio:Yeah, it was. I hadn't seen him in ages.
Angela:But he skipped out on his last month's rent and stole your girlfriend!
Yukio:Yeah, yeah. That's water under the bridge. In fact we're going to be roommates again!
Angela:You're letting him move in with you again after what he did? You're a knucklehead!

Dialog 2 give someone a hand [ 手伝う ]

Angela:Excuse me. Can I give you a hand with your wheelchair?
Yukio:Oh, thank you so much! I can't get up this very steep ramp.
Angela:No problem. Here you go.
Yukio:You're the first person who offered to give me a hand. I've been struggling for a few minutes.
Angela:Wow, that's unbelievable. The station is so crowded with lots of people walking by.