So am I, I am too, Neither am I, etc

1. Look at this.

She is saying that she is also tired.

2.- Here are some more examples:

He was very angry. ----> So was I

My flat's quite small. -->So is mine.
They were waiting --> So was she.
I'm going to have tea --> So am I
Ann has finished her work and so has Mary.
They've been waiting. --> So has she.
I work in an office. --> So do I.
I enjoyed the film.--> So did I.
Philip will pass the exam and so will you.
He can drive. --> So can she.

Note:

----> we use so after a positive statements;
----> the verb we use after so depends on the verb used in the positive statement.

3.- Instead of so am I, we can say I am too, with the same meaning. Here are some examples:

I'm tired. ---> I am too.
We've got a small flat. ---> We have too.
I work in an office. ---> I do too.
Bill enjoyed the film and I did too.

4.- We can use expression like neither am I to reply to a negative statement:

I'm not tired. ----> Neither am I (= and I'm not tired.)
I haven't seen that film.---> Neither have I
I don't like this pleace. ---> Neither do I
I didn't see that play. ---> Neither did I
His sister can't drive and neither can he.

5.- We can say I'm not either to mean the same as neither am I:

I'm not tired. ---> I'm not either. (= And I'm not tired.)

I haven't seen that film. ---> I haven't either.
I don't like this place . ---> I don't either.
I didn't see that play. ---> I didn't either.
His sister can't drive and he can't either.