English — Additions: so/neither do I
To say "the same is true for me", English uses short additions that copy the auxiliary and match the polarity. For a positive statement use so: "I love coffee." — "So do I." For a negative statement use neither or nor: "I don't smoke." — "Neither do I."
How it works
The addition takes the same auxiliary or modal as the first sentence, and only I inverts after so/neither. With no auxiliary present, do/does/did stands in: "He works hard." — "So do I." "She can swim." — "So can I." "They won't come." — "Neither will I." After a positive be sentence use "So am I / So is he"; after a negative one use "Neither am I / Nor am I."
Examples
| First statement | Addition (agreeing) |
|---|---|
| I love coffee. | So do I. |
| She is tired. | So am I. |
| He can drive. | So can I. |
| We went early. | So did I. |
| I don't smoke. | Neither do I. |
| They aren't ready. | Neither am I. |
| She won't wait. | Nor will I. |
| I can't swim. | Me neither. |
Good to know
"Me too" and "Me neither" are informal and never invert (say "Me neither," not "Me neither do I"). Don't cross the polarity: agreeing with a negative needs neither/nor, so "I don't drink." — "So do I" is wrong; use "Neither do I." To disagree instead, keep the auxiliary but drop so/neither: "I love coffee." — "I don't" / "I don't smoke." — "I do."