1.is的复数形式是are
2.is 的过去式是 was
3.was的复数形式是were
拓展：
is vt.& vi. 是（be的三单形式）
n.存在.高考
过去式:was
双语例句：
1.This man is an animal, a beast
这人是个畜生，是个野兽。
2.Clearly there is a problem here
显然，这里出了个问题。
3.This is a common fallacy which has no basis in fact.
这是一个没有事实依据的常见谬误。
4.Choosing the right type of paint for the job is half the battle.
选对了涂料，这项工作就成功了一半。
5.My life is ruined and I suppose I only have myself to blame.
我的一生都毁了，我想这只能怪我自己。
6.I think that it is not coincidental that we now have arguably the best bookshops in the world.
我认为我们现在拥有了可以说是世界上最好的书店，这并非巧合。
7.Their purpose is to build a fair society and a strong economy
他们的目的是要建立一个公平的社会和一个强大的经济体。
8.In business circles he is noted for his flair and clarity of vision.
在商界，他的天赋和远见卓识是出了名的。
9.The new government's first challenge is the economy.
新政府面临的第一个难题是经济问题。
10.This has fuelled speculation that heis about to clinch a deal with an American engine manufacturer.
这更增添了人们对他即将和美国的一家发动机制造商达成协议的猜测。