名詞不定詞在be動詞後做主詞補語

My plan is to see him.

His only wish at present is to sleep.

His goal is simply to become a teacher.

His resolution is to be a teacher.

1)名詞不定詞可作主詞,亦可作be動詞後的補語

To see is to believe.

=Seeing is believing.

To love her this way is to worship her.

=Loving her this way is worshipping her.

2)下列句型中be動詞之後的to可省略,改接原行動詞作補語

1.What you should do is (to) apologize to him.

2.All you have to do is (to) take a good rest.

3.All I can do is (to) wait.

4.All I did yesterday was (to) eat and sleep.