to act in a particular way

She always behaves well/badly when her aunts come to visit. 每当她姨妈来作客时，她总是表现很好／很差。

Whenever there was a full moon he would start behaving strangely. 每当月圆之时他就行为怪异。

They behaved as if nothing had happened. 他们表现得好像什么也没有发生过一样。

to show particular behaviour in a particular situation or under particular conditions

They learn how particles behave in solids, liquids, and gases. 他们了解到粒子在固体、液体和气体中如何运动。

It is believed that animals behave differently before a natural disaster. 据信动物在自然灾害发生之前会行动异常。

to be good by acting in a way that has society's approval

Did the children behave (themselves)? 孩子们守规矩吗？