AGREEING AND DISAGREEING: So do I & Neither do I

To agree with a positive statement
We use so + auxiliary\modal verb + pronoun
+ "I like tea without sugar.'
+ 'So do I.'
To agree with a negative statement
We use nor/neither + auxiliary\modal verb + pronoun:
+ "I don't like tea with sugar.'
+ 'Nor do I.' or 'Neither do I.'
To disagree with a positive statement
We use pronoun + auxiliary\modal verb + not (-n't):
+ "I like tea without sugar.'
+ 'I don't.'
To disagree with a negative statement
We use pronoun + auxiliary\modal verb
+ "I don't like tea with sugar.'
+ 'I do.'