过去式 were；过去分词 been；
are
v./aux.是（be的第二人称单复数现在时，第一、三人称复数现在时）；
n.公亩(等于100平方米)；
现在分词 being
They are one of this year\'s hot new bands.
他们是今年走红的新乐队之一。
We are still friends, though, which is good.
不过我们仍然是朋友，这令人感到欣慰。
A new system has been devised to control traffic in the city.
控制城市交通的新系统已经设计出来。
