at后面加什么动词

　　He's an expert at getting his own way.

　　他在如何达到自己的目的方面很在行。

　　The weather is very changeable at this time of year.

　　年年在这个时候天气都变化无常。

　　Almost all homes have at least one TV set.

　　差不多每家都至少有一台电视机。

　　I was still in short trousers at the time.

　　我那时还在穿着短裤呢。

　　Both their children are at university.

　　他们的两个孩子都在上大学。