So and neither

Vicky: I'm hungry.

Rachel: So am I.I haven't eaten anything all day.

Daniel: Neither have I. I didn't have time for breakfast.

We use so after a positive statement and neither after a negative one. I'm hungry. ~ So am I. (= And I'm hungry./I'm hungry, too.) / haven't eaten. ~ Neither have I. (= And I haven't eaten./I haven't eaten either.)

The structure is so/neither + an auxiliary + the subject.

The auxiliary is a form of be or have or a modal verb, e.g. can.

We're really busy at work. ~ So are we. Tom has gone to the match. ~ And so has Nick.

David can't drive, and neither can Melanie. The subject comes at the end. NOT We're busy. ~ So we are. In the present simple and past simple we use a form of do.

I love old cowboy films. ~ So do I. This phone doesn't work. ~ Neither does this one.

United won, and so did Rangers.

We can use nor instead of neither.

Emma isn't here tonight. Neither/Nor is Matthew

Fuente: Oxford practise grammar.