SO, TOO, ALSO NEITHER , EITHER

SO / ALSO / TOO = +

So am / do / can / will, etc I
SO is used to show agreement with POSITIVE statements.
SO + Auxiliary + Subject (pronoun)
The Auxiliary needs to agree with the verb tense in the original statement.
It is similar to using ALSO & TOO in a sentence

EXAMPLES:
I am happy. So am I.
= I am happy too.
= I am also happy.
I'm going to Brazil. So am I.
=I am going to Brazil too.
= I am also going to Brazil.
You look nice today. So do you.
Present Simple = You look nice too.
= You also look nice.

EXAMPLES:
We went to the concert So did we.
last night. Past Simple = We went to the concert too.
= We also went to the concert.
He will win a prize. So will I.
= I will win one too.
= I will also win one.
I can speak 2 languages. So can I.
= I can do that too.
= I can also speak 2 languages

EXAMPLES:
He should study more. So should I.
= I should study more too.
= I should also study more.
Stephanie has a cat. So does Mary.
Present Simple = Mary has one too.
Present Perfect = Mary also has a cat.
They have finished So have I.
their homework. = I have finished too.
= I have also finished my homework

NEITHER & EITHER

NEITHER
Neither is used to show agreement with negative statements.
Neither + Auxiliary + Subject (pronoun)
The Auxiliary needs to agree with the verb tense in the original statement.
It is similar to using either at the end of a sentence, although Neither is more commonly used, especially in spoken English.

EXAMPLES:
I don't understand Spanish. Neither do I.
= I don't understand Spanish either.
I cannot swim. Neither can I.
= I can't swim either.
I am not hungry. Neither am I.
= I'm not hungry either.
I = Me neither.

EXAMPLES:
Mary didn't go to the party. Neither did we.
= We didn't go either.
I wouldn't like to do his job. Neither would Sam.
= I wouldn't like to do it either.
He won't stop talking. Neither will they.
= They won't stop either.
I haven't passed my exams. Neither has Jane.
= Jane hasn't passed either.
You shouldn't talk in the movie. Neither should you.
= You shouldn't talk either.