Altruism: giving things away with no certain return is odd behaviour in evolutionary terms. It may help with group bonding or simply give pleasure.

利他行为：从进化角度上看，一味给予而不求回报是件怪事。这可能对团队融合有益或纯粹出于高兴。

One particular English pilot was so embarrassed at being taken there that word of his odd behaviour reached the ears of an informer.

一名英国飞行员送来之后，尴尬不安， 以至举止异常，消息传到告密者耳中。

I took her on one side to ask about her odd behaviour.

我把她带到一旁问她为什么有这种奇怪举动。

But then I sort of connected it with the dog, with his odd behaviour.

但后来我不由得把它和狗的奇怪行为联系到一起。