So, Too, Either, Neither

So and Too
The words so and too are used to combine two positive statements with identical predicates to form a compound sentence. The predicate is not repeated completely in the second part of compound sentence. An auxiliary must be included in the second part of the sentence.





Either and Neither
The words either and neither are used to combine two negative statements with identical predicates to form a compound sentence. The predicate is not repeated completely in the second part of compound sentence. An auxiliary must be included in the second part of the sentence.

My problem:
In so, too, either, neither we use an auxiliary verb in each sentence. What is the auxiliary verb that we have to use?
After I browse and search about these materials, I found that we have to use the auxiliary verb that is suitable with the tense in the sentence. Look at these example:

• Eldo go to Palangka Raya and so do I. / Eldo go to Palangka Raya and I do too.
• Eldo went to Palangka Raya yesterday and so did I / Eldo went to Palangka Raya yesterday and I did too.
• Eldo will go to Palangka Raya tomorrow and so will I / Eldo will go to Palangka Raya and I will too.

• Asep doesn’t come and Lisa does not either / Asep doesn’t come and neither does Lisa.
• Asep didn’t come and Lisa did not either/ Asep didn’t come and neither did Lisa
• Asep will not come and Lisa will not either/ Asep will not come and neither will Lisa.