Well, I found these two sentences yesterday
and, to be honest, I don?t know what is
the difference between the usage of
an infinitive with “to” and “without” to?
1.- All we have to do is SIGN a few documents…
2.- My plan is TO EXPLAIN…
Well, I would like to know if it?s possible
to use the infinitive with or without “to”
indistinctively in both sentences.
And… Could I do it as well in any sentence?
Actually this grammatically incorrect. Strictly speaking it should be “. . we have to do is to sign . .”, but it is accepted to drop the “to” after “to do”.
If you said “doing” it would be followed by “-ing”:
"What we are doing is signing . . ".
Sorry, dOlier, my opinion is a bit different. Both the sentences given below are grammatically correct! To after the expressions like All I did was is just optional.