all he did was "ask" or "asking"?

"asking" - In this case this kind of language element is called gerund, right?

In high school my teacher firmly told us two verbs can never be together (25 years later I can still remember her angry face).

But I do see a lot of sentences like this, in some literature:

All he did was ask a question.

I am pretty sure my English teacher wouldn't be happy with this and would put a big "X" next to it. She told us you either convert the latter verb to an infinitive or a gerund, so it is either:

All he did was asking a question.

or:

All he did was to ask a question.

So is the first writing grammatically right? And if it is, is there any difference in meaning of the three sentences?

Solution 1:

Yes! And an English teacher wouldn't put a big "X" next to it. He will instead be happy that you know better than others. Because it's acceptable in English to use "bare infinitive " after "do/does/ did " in this sort of sentences. So you can write -

1) All he did was ask a question.

or

All he did was to ask a question.

or

All he did was asking a question.

But The last one, I think, is best.