be动词都有am/is/are/was/were，那么，它们的具体用法是什么呢?下面小编告诉你七年级上册英语动词be的用法，大家一起来看看吧!
七年级上册英语动词be的用法:
第一，be动词都有:am/is/are/was/were。都表示“是”的意思，在句子中充当谓语动词的成分。
第二，在一般现在时中，当主语是第一人称的时候，谓语动词可以用am。比如:I am a boy.我是一个男生。
第三，在一般现在时中，当主语是第三人称he/she/it，又或者是名词单数的时候，后面的谓语动词可以是is。比如:He is a student.他是一个学生。The apple is red.这个苹果是红色的。
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第四，在一般现在时中，当主语是they/we，又或者是名词复数时，后面的谓语动词可以是are。比如; We are good friends.我们是好朋友。The trees are tall.这些树是高的。
第五，在一般过去时中，当主语是it/he/she/I/名词单数时，谓语动词可以用was，不然就用were。比如:It was red dog.它是一只红色的狗。They were very happy.他们很高兴。
There be句式的特殊用法:
▲ 英语中的 There，除了表示地点“在那里”外，还有一个非常重要的用法，就是:充当引导词的角色，同时，引起句子结构上的倒装。具体表现在:
1. There be 存在句:——最原始最典型的倒装
谈到倒装句，人们都不陌生，认为它是一个很重要的句式。其实，在一个人刚刚开始学英语的时候，就已经学到了真正意义上的倒装句:There be 句型。
There is a book on the desk. 去掉引导词 There，原来的倒装句则变成:A book is on the desk.
What is there on the desk? 实际等于说:What is on the desk?
There be是倒装句，表存在，不必细说。
2. There + 不及物动词 + 主语:——最常见的倒装
There lived an man in the forest long ago. 很久以前，森林中住着一位老人。
There stands a temple on the top of the mountain. 山顶上有一座庙。
There goes the bell. Let’s have our class. 铃声响了，我们上课吧。
最后一句 There goes the bell. There 除了引起句子结构的倒装外，还提醒听者注意。
3. “There + be + 过去分词 + 主语” 和“There + be + 过去分词 + 主语”——最特殊的倒装
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▲“There + be + 过去分词 + 主语”，其实是被动语态的变式，去掉引导词 There，还原本来面目。现在，我直接使用网友的句子为例:
There are now published millions of books very year in China .
等于:Millions of books are now published very year in China.
On the following day, there was held a splendid banquet.
等于:On the following day, a splendid banquet was held.
There was shown at the exhibition an electronic computer made in Shanghai .
等于:An electronic computer made in Shanghai was shown at the exhibition.
▲“There + be + 现在分词 + 主语”，其实是不及物动词进行时态的变式，去掉引导词There，还原本来面目。现在，我直接使用网友的句子为例:
There were running in the garden a group of children aged from seven to twelve.
等于:A group of children aged from seven to twelve were running in the garden.
there be结构的be的活用:
■there be 结构中的be必须随着be后面名词的数及句子后面的时间，使用不同的形式或时态。如:
(1) There are fifty chairs, desks and a blackboard in our classroom. 我们的教室里有五十把椅子、五十张课桌和一块黑板。
(比较) There is a blackboard, fifty chairs and desks in our classroom. 我们教室里有一块黑板、五十把椅子和五十张课桌。
(2) There weren’t any high buildings in the village twenty years ago. 二十年前，村子里没有高楼大厦。
■there be结构可与情态动词can, could, will, would, must, may, might, ought to 及某些不及物动词seem, appear, happen等连用，如:
(1) Do go into the hole, for there can be snakes in it. 不要进到洞里面去，因为洞里可能有蛇。
(2) The car doesn’t run. There must be something wrong with it. 车不走了，肯定出了毛病。
(3) There seemed to be some people in the room, for the water is still hot. 房间里原来似乎有人，因为水还是热的。
(4) There happened to be a policeman there. 碰巧那儿有个警察。
■有时为了使句子表达生动，动词be 可换成 come, live, remain, stand, lie, appear, exist, seem, remain, …. 。如:
(1) Long ago, there lived a king who loved horses very much. 很久以前，有个非常喜欢马的国王。
(2) There stands a house on the top of the mountain. 山顶上有座房子。
(3) There exists some doubt in what he said. 在他所的话中有些疑点。
■there be 结构不能跟 have(有) 连用，但可跟 have / has + 过去分词，或 have /has to + be / stand / lie 等动词原形等连用。如:
(1) The man liked to plant trees, and soon there have been tall trees around his house. 那个人喜欢种树，不久他房子的周围就有了很多大树。
(2) There has to be air and water on the planet for living things to live on. 在那颗行星上必须要有能使生物生存的空气和水。
there be 句式的语法要点:
一、概说
英语中的there be结构主要表示某处存在有某物，所以通常被称为存在句。其中的there为引导词，无词义，be为谓语动词，there be后面的名词为句子主语。
二、there be结构的主谓一致问题
在there be句型中，若句子只有一个主语，谓语的数则取决于该主语的数;若有几个主语并列，则通常是与靠近的主语保持一致。如:
There is no cause for anxiety. 不必焦虑。
There is some dirt on your coat. 你的外套上有灰尘。
There are twenty children present. 在座的有20个孩子。
There is a teacher and some students over there. 那边有一位老师和一些学生。
三、there be结构的时态问题
there be结构的时态由其中的谓语动词be来体现，它可以有一般现在时、一般将来时、一般过去时、现在完成时以及过去完成时等多种时态形式。如:
There will be a rise in unemployment next year. 明年失业人数将会增加。
There have been a series of car accidents at the crossing. 在这个交叉路口已发生了一连串的车祸。
There had been two sea fights between them. 他们之间发生了两场海战。
四、there be结构与情态动词连用
there be结构有时可以与情态动词连用。如:
There may be an opportunity for you to see the premier. 你可能有机会见到总理。
There must be something wrong with my left arm, which is asleep.我的左臂发麻，一定出什么问题了。
There used to be a lot of troubles in that region. 那个地区过去动乱不断。
五、there be结构的非谓语形式
there be结构的非谓语形式有两种基本结构，即there being和there to be。一般说来，there being结构主要用作状语或介词宾语;There to be 结构主要用作动词宾语。如:
There being no further business, I declared the meeting closed. 没有更进一步的情况(讨论)，我就宣布闭会。
There is now some hope of there being a settlement of the dispute. 现在有点希望可以解决这次争端。
We expect there to be more discussion about this. 我们期望能对此展开更多的讨论。
注:用作介词宾语一般用there being，但用作介词for的宾语时，只能用there to be。比较:
They planned on there being another meeting. 他们打算再开一次会议。
They planned for there to be another meeting. 他们打算再开一次会议。