A teacher's job is to.His job is to.Our plan is to.这些be动词后都加

没有这样的规定的.
A teacher's job is teaching
=A teacher's job is to teach.
也可以倒过来说：
Teachinig/To teach is a teacher's job.
My habbit is getting up early.
=My habbit is to get up early.
也都行的.
有人说
doing是抽象的动作
而
to do是具体的动作,也就是要发生的动作的.
Our plan is to start soon.
我的计划是马上出发.（就要发生的）
但如果用在这个结构中,其实都差不多的.
要注意的就是
想知道be doing是进行时,还是be+表语
只要把doing跟主语换个位置就行了.
如：
My work is teaching.
=Teaching is my work.
He is working
就不能换成
working is he了.
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再答： ��ʵ�� A teacher's job is teaching students.Ҳ����ȫ���Եġ� ������仰����û�о��巢��ġ� ��ʦ�Ĺ������ǽ�ѧ����ѧ��û�о��巢��ѽ�� ���ڻ���������һ���ˡ� ���ۣ� û������Ĺ涨�ġ�
再问： 介个.......我也不想纠结的呀....我是预备的学生书上是这样的'Qu Yuan's job was to give advice to the king.'然后就...每次做选择题的时候，就有那么一大堆....这怎么办
再答： Qu Yuan's job was to give advice to the king. =Qu Yuan's job was giving advice to the king. =Giving advice to the king was Qu Yuan's job. ��˼û��ʲô��ͬ�ġ�