首先科普一下。不叫be动词，叫动词be。有区别吗？有。这是个动词分类问题。英文的动词分为四类，实义动词，联系动词，情态动词和助动词，实义动词还能分成及物动词和不及物动词。及物动词还能分成，单宾语动词，双宾语动词，和复合宾语动词，没有了，就这么多。
动词be是一个词，不是一类词。如果能说be动词，那我就可以说take动词， run动词play，动词， walk动词，这岂不是乱了套了？没有一本语法书把它叫be动词。如果有，那作者绝不是语法学家，太不严谨了。现在说说它的用法吧。动词be主要有三种用法，一，作系动词，它的意思是“是” “存在”“成为”等。
I am a doctor 。是I will be doctor after graduation 。成为There’s a table in the house。存在二，作为所有进行时的助动词。助动词be用在八个进行时中。用作进行体的助动词时，它的后面要接动词的现在分词形式，也就动词➕ing的形式。
和系动词be一样，它也有八种形式，原形be，现在时第一人称am第二人称are，单数第三人称is，过去时第一和第三人称was，单数第二人称和复数所有人称were，现在分词being，过去分词been。英文有八个进行时，I am doing my homework。
现在进行时I was doing my homework。过去进行时I will be doing my homework。将来进行时I would be doing my homework。过去将来进行时I have been doing my homework。
现在完成进行时I had been doing my homework。过去完成进行时I will have been doing my homework。将来完成进行时I would have been doing my homework。
过去将来完成进行时这些时态中都含有动词be三，用在被动语态的助动词，这时，动词be后面要接动词的过去分词形式。也就是-ed形式。The church is visited by thousands of people。一般现在时被动语态The church was visited by thousands of people。
过去时被动语态The church will be visited by thousands of people。将来时被动语态The church would be visited by thousands of people 过去将来时被动语态The church is being visited by thousands of people。
现在进行时被动语态The church was being visited by thousands of people。过去进行时被动语态The church has been visited by thousands of people。
现在完成时被动语态The church had been visited by thousands of people。过去完成时被动语态The church will be visited by thousands of people。将来时被动语态The church would be visited by thousands of people。
过去将来时被动语态所有这些句子里的动词be的各种形式，都是没有意义的，只是帮助实义动词构成各种时态。都不要翻译。
