B-21：blunder upon 无意中发现

A:Is this watch yours?

A:这是你的手表吗?

B:No, it isn't mine. I blundered upop it under the sofa. Do you know whose watch it is?

B:不是我的，我在沙发下面拣到的。你知道是谁的吗?

C:Let me have a look. It's mine. I have been looking for it, but just can't find it. It's a present from my father.

C:让我看一看，这是我的手表，我一直在找它，就是找不到。这是我父亲送我的礼物。

B:Well, here you are. Remember to put it in a proper place.

B:噢，给你吧，记得把它放好。