Me too, So do I, So am I. . Those are used as short statements to show we share the same (positive)circumstances with the previous statement. . If there is "be" (am/is/are) in the sentence, you should reply with "so am I". . If there is verb without 'be verb' in the sentence, you should use "so do I". . I am tired. - Me too. (auxiliary - the verb "to be" )
Tag questions (or question tags) turn a statement into a question. They are often used for checking information that we think we know is true. Tag questions are made using an auxiliary verb (for example: be or have) and a subject pronoun (for example: I, you, she). Negative question tags are usually contracted: It's warm today, isn't it (not 'is it not'