be是英语动词中比较特殊的一类动词，其使用频率很高，牵涉到各种句型、时态和语态等用法，下面小编告诉你英语中动词be的用法规律，大家一起来看看吧!
英语中动词be的用法规律:
(一)be的时态变化
系动词be会有一般现在时、一般过去时、一般将来时、现在完成时、过去完成时等的时态变化。如:
He isa student.
They werein the park yesterday.
It will be cloudy tomorrow.
He has been ill for six days.
It had been three hours before she left the hat shop.
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(二)be与情态动词的连用
其用法为:情态动词+系动词be原形。如:
It must be Lucy's book. Her name is on the cover.
It can be very difficult for us to memorize too many words within such a short time.
She should be here on time tomorrow.
助动词be的用法:
1. be +现在分词，构成进行时态。如:
They are having a meeting. 他们正在开会。
We were planting trees this time yesterday. 我们昨天这个时候在植树。
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2. be + 过去分词，构成被动语态。如:
The door was broken by Tom. 门是汤姆打破的。
English is taught in our school. 我校教英语。
3. be + 动词不定式，可表示:
A. 打算、决定、计划、安排等。如:
He is to visit Japan next week. 他决定下周访问日本。
I was to have told you yesterday, but you were not in. 我本打算昨天告诉你的，但你不在家。
B. 指示、命令、禁止等，即“必须，一定”。如:
You are to hand in the exercises tomorrow. 你们明天必须交练习。
You’re not to (=You mustn’t) smoke here. 你不可以在此处抽烟。
C. 责任、义务、需要，即“该不该”。如:
You are to (=should) report to the police. 你应该报警的。
Am I to go on with the work? 这工作我该不该继续干下去?
D. 可能性，与can, may相当，不定式多用被动式。如:
The book was not to (=could not) be found. 那本书可能找不到了。
E. 假设，用于虚拟条件句中。如:
If it were to rain, we would get wet. 要是下雨，我们就会淋湿。
F. 表示注定要发生或后来必然发生。如:
This experience was to change his life. 这次经历注定要改变他的生活。
注:不定式作表语与上述用法是不同的。如:
My idea is to go there today. 我的意思是今天就去那里。
be的一种特殊用法:
在新课标人教版选修六第5单元中，有这样一个句子:I’ll never forget my first sight of an eruption. It was in the second week after I arrived in Hawaii. 第2句中的 was 是系动词无疑，但没有“是”的意思。那么，在这里是什么含义呢?回答这个问题，首先要搞清楚主语It指代什么。显然 It 指代上文的 eruption。既如此，was 应该是“发生”的意思，相当于 happened 或 broke out。
这就是动词be 的一个特殊用法，其主语往往是表示“事件”的名词，如:meeting, talk, lecture, report, discussion, match, game, party, concert, play, accident, eruption, event等。因此，上句译成汉语应该是:我永远忘不了我第一次看见火山喷发时的情景，那(指“火山爆发”)是发生在我抵达夏威夷的第二个星期之后。又如:
---When was her birthday party? ---It was the night before last. 她的生日派对(聚会)是何时举办的?前天晚上。(was 等于 was held)
Our school sports meet will be next week. 我们学校的运动会将在下周举行。(be等于take place)
It was reported that the accident was on Tuesday and five people were killed. 据报道事故发生在星期二，有五人丧生。(was等于happened)
This is when small amounts of gases in the atmosphere, like carbon dioxide, methane and water vapor, trap heat from the sun and therefore warm the earth. (选修6第四单元，Reading) 这种现象(温室效应)发生在大气层中少量的气体，如二氧化碳，甲烷，水蒸气等，吸收太阳的热量，因而使地球变暖的时候。(is等于takes place)
下列两句很有意思，一字之差，但意思相差甚远。请比较:
It was Sunday. We went out for a picnic.
It was on Sunday. We stayed at home and didn’t know anything about the accident.
有人把 It was Sunday. 和 It was on Sunday. 混为一谈，认为意思没什么区别。其实，这两个句子的含义大不一样。前者译为“时间是星期天”，It 指时间;后者译为“事情发生在星期天”，It 指某个事件。
一般说来，be 表示“发生”意义时，除了它的主语表示“事件”概念外，还往往有一时间状语跟它连用。
关于be fortunate to do sth结构的说明:
■若其中的动词be为现在式(am, is, are)，则其后不定式通常只能是静态动词，不能是动态动词。如:
They are fortunate to be able to buy such a large a house. 他们真幸运，能买那样大的房子。
但不能说:They are fortunate to buy such a large house.
■若要在am [is, are] fortunate后接动态动词，则要用完成式或进行式。如:
They are fortunate to have bought such a large house. 他们很幸运，买了那样大的房子。
You are fortunate to be working in London. 你真是幸运，能在伦敦工作。
■若其中的动词be为过去式(was, were)，则其后不定式便没有以上限制。如:
He was extremely fortunate to escape without injury. 他能安然无恙地逃脱，真是太幸运了。
He was fortunate to have had the chance of doing so. 他很幸运有机会这样做。
■be fortunate后接不定式与接从句意思稍有不同:It is fortunate that…的意思是“……是件好事”，而“主语+be+fortunate to do sth”则强调主语的好运气。如:
It’s fortunate for us that he has a rich uncle 他有一位有钱的叔叔是我们的运气。(如可以替我们借钱)
He’s fortunate to have a rich uncle. 他真幸运有一位有钱的叔叔。(许多人没有)
