Addition to a remark

When someone gives a fact, you can call that a remark. And you can react to what is said. By adding something that agrees with what is said: an affirmative addition. Or by adding something that is in contradiction with what is said: a negative addition.

Affirmative addition
to an affirmative remark: SO + Auxiliary + Subject	John is still waiting. So am I. They were watching TV. So were we.
to a negative remark:: NOR/NEITHER+ Auxiliary + Subject	Last time Helen didn't pay attention. Nor did Pamela Stella won't like your answer. Neither will Mark.
Negative addition

to an affirmative remark: BUT + Subject + Auxiliary		They have been late before. But we haven't. William will come tomorrow. But Bill won't.
to a negative remark: BUT + Subject + Auxiliary	Hey, that's exactly the same!	I don't like tea. But I do. We haven't seen anything like this before. But we have.

Attention

In an addition we always use
the same auxiliary as in the remark.

And if there is no auxiliary in the remark:
use DO

Bob is going to explore the village.
So are we.
But Sarah isn't.

Ann understands Italian.
So does Brent.
But Andrew doesn't.

It is the same auxiliary as in the remark,
but the form may be different:
after all the subject in the addition is also different.

Fred is riding his bike.
    So is Mike.
    And so am I.
    And so are they.

In a negative addition you disagree with what the remark says,
so the auxiliary is in the opposite form as well.

Mia has written many letters.
But I haven't.
Kelly doesn't often drink wine.
But Harriet does.