I think so, I hope not; so do I

I think so, I hope not

When the missing part is a whole idea, so stands in for it:

• Is she coming? - I think so. - I think she is coming.
• Will we make it? - I hope so.
• Is this the right road? - I suppose so.

For a not answer, the verbs split into two groups:

I think not is correct, but formal and old-fashioned. I don't think so is the everyday answer.

I'm afraid so and I'm afraid not give bad news politely:

So do I, neither do I

To agree, say so + helper + I. To agree with a not sentence, say neither + helper + I. The helper comes before I.

1234

1. 1I'm reading.
2. 2So am I!
3. 3I'm reading.
4. 4I'm not!

Left: the girl says I'm reading, and the boy, reading too, says So am I. Right: the girl is still reading, but the boy is playing football, so he says I'm not (not reading).

The helper must match theirs: So did I after a past verb, So would I after would. Nor works like neither:

In relaxed speech, me too agrees with a yes sentence and me neither with a not sentence. (Me either is also heard in American speech.) More in both, either and neither.