Teacher Club A2: either / neither / so / too

In Positive Statements

1. Using 'So'

Grammar: So + auxiliary/modal verb + pronoun

Note:
We should pay attention to the verb tense used in the statement while choosing our auxiliary form.

Speaker A’s Statement	Speaker B
Celine is watching TV.	So am I.
Sam can speak French fluently.	So can I.
Terry has completed his master’s degree.	So has James.
His parents should be more responsible.	So should we.
Stephanie was so worried yesterday.	So was I.
Mary and Sam will join the chess club.	So will Jessica.
Nathan looks so confident.	So do I.

2. Using 'Too'

Grammar: Pronoun + auxiliary/modal verb + Too

Speaker A’s Statement	Speaker B
Celine is watching TV.	I am too.
Sam can speak French fluently.	I can too
Terry has completed his master’s degree.	James has too.
His parents should be more responsible.	We should too
Stephanie was so worried yesterday.	I was too
Mary and Sam will join the chess club.	Jessica will too
Nathan looks so confident.	I do too.

In Negative Statements

1. Using 'Neither / Nor'

Grammar: Neither (nor) + auxiliary/modal verb + pronoun

Speaker A’s Statement	Speaker B
Derek isn't sleeping.	Neither (nor) am I.
Sandra cannot play the guitar.	Neither (nor) can I.
Jennifer hasn't eaten her sandwich.	Neither (nor) has James.
They shouldn't complain.	Neither (nor) should we.
Stephanie was not worried at all.	Neither (nor) was her husband.
Mary and Sam won't attend the meeting.	Neither (nor) will I.
Dogs cannot fly.	Neither (nor) can cats.

Note:
Although there is a negative statement, we use a positive auxiliary form. Speaker A: He isn't guilty. Speaker B: Nor is Tom. (Not Nor isn't Tom.)

2. Using 'Either'

Grammar: Pronoun + auxiliary/modal verb + Either

Speaker A’s Statement	Speaker B
Derek isn't sleeping.	I am not either.
Sandra cannot play the guitar.	I can't either.
Jennifer hasn't eaten her sandwich.	James hasn't either.
They shouldn't complain.	We shouldn't either.
Stephanie was not worried at all.	Her husband wasn't either.
Mary and Sam won't attend the meeting.	I will not either.
Dogs cannot fly.	Cats can't either.

In Informal Interactions

When speaking or in less formal writings, regardless of tense, we can use “me too” and “me neither” in firt person.

All the following examples are acceptable

A: I have been studying a lot recently.
B: Me too.

A: He never attended the class regularly.
B: Me neither.

A: I haven't been feeling very well.
B: Me neither.

(taken from http://www.grammarbank.com/so-neither-either-too.html)

Explanations in video: