一般在什么情况下用“be”这个单词？

比如It's good to be a teacher.
不定式可以用
还有一些专门后面接动词原型的地方 比如will 后面

be是is, are, am的原型
在to后，如I want to be a teacher.
Don't后面Don't be annoyed.
Be good, do right.
不是概括，只是我暂时想到的，希望能帮到你。

不定式 to be myself
需要跟原形的动词后面make/have/...+sb./sth.+be ...(被动时)
被动时态的进行时,he is being examined ,用be-ing

你问的真好，形容词/名词前面阿

用在一些只能接动词原形的地方

/bɪ; bɪ; strong form 强读式 biː; bi/ v =>Usage at be2 用法见be2. 1 (used after there and before a/an, no, some, etc+ n 用於there之后及a/an、no、some等+名词之前) (a) exist; occur; live 有; 存在; 生存: Is there a God? 有上帝吗? * For there to be life there must be air and water. 一定要有空气和水才有生命. * There are no easy answers. 现成的答案是没有的. * There are many such people. 这样的人多的是. * Once upon a time there was a princess. 从前有一个公主. * There have been cows in that field since my grandfather's time. 从我祖父那时候起, 那片地上就养著牛. (b) be present; stand 在; 在场: There's a bus-stop down the road 路的前方有一个公共汽车站. (Cf 参看 The bus-stop is