像is、was、were、am、are这些都是be动词么？为啥叫动词？和一般动词有啥区别？

be
助词 v.aux.
1. (与动词的现在分词连用,构成各种进行时态)正在...,在...
I won't be free this afternoon. I'll be seeing a friend off.
我今天下午没空,我要给朋友送行。
What were you doing from 9 to 11 this morning?
今天上午九点到十一点你在做什么?
He is working.
他在工作。 2. (与及物动词的过去分词连用,构成被动语态)被...
The problem was solved long ago.
问题早解决了。
It will be discussed tomorrow.
此事将在明天讨论。 3. 【旧】(与不及物动词go,come,rise等的过去分词连用,构成完成时)已经...
The sun is set.
太阳已经下山。 4. (与动词不定式连用,表示职责、义务、意图、约定、可能性等)应该做...,必须做 ...;预定做...;会做...
The President is to visit Japan next week.
总统将于下周访问日本。
You're to do your homework before you watch TV.
你应该做了功课再看电视。
不及物动词 vi.
1. 是[L]
At that time he was the chair of the department.
当时他是系主任。
I am a teacher and they are my students.
我是老师,他们是我的学生。
She is very young.
她非常年轻。 2. (表示时间、度、量、价值等)是;值;等于[L]
The watch is 100 dollars.
这表值一百元。 3. (常用祈使语气或不定式)要,得;成为;变成[L]
Be quiet, please.
请安静。 4. (与there连用)有[L]
There are a lot of tourists there.
那里有许多观光客。 5. 逗留,(继续)呆[L]
He will be here all next week.
下周他将一直呆在这儿。 6. 在[Q]
Tony is in the office.
托尼在办公室里。 7. 存在
Whatever is has every reason for being.
存在的东西总有其存在的理由。 8. 听任
If she's sleeping, let her be.
如果她在睡觉,就别惊动她。

系动词+表语做系表结构本身没有意义

中国话就是 是