Why is the following example (A) correct as a cleft sentence, but not sentence (B)?
As I have learned, we can only use 'pronoun, noun, gerund, or infinitive', not the base form of verb (help) after noun clause. I get confused.
A "All (that) I did was touch the window, and it broke."
B "What makes me feel happy is help the poor."
Are these following sentences correct grammatically and logically?
All (that) I did was (to) touch the window, and it broke.
All (that) I did was touch the window, and it broke.
All (that) I did was touching the window, and it broke.
What makes me feel happy is to help the poor.
What makes me feel happy is helping the poor.
What makes me feel happy is help the poor.
Best Answer
Because the bare infinitive help is not understood to be a nominal (which goes with what I like) but an action. What I want to do is help the poor. What makes me happy is to help|helping the poor.
I like look out the window. ungrammatical
I like looking out the window. grammatical
I like to look out the window. grammatical
Cleft:
What I like is look out the window.ungrammatical
What I like is looking out the window. grammatical
What I like is to look out the window. grammatical
Normal: I touched the window.
Cleft: What I did was touch the window.
The predicate complement of the cleft must supply either a nominal or an action according to the needs of the verb in the cleft.
Here, that verb is did, and it is looking for an action. When did has the meaning "performed an action" it wants an action complement. The bare infinitive is an action:
I did shop. grammatical
I did eat. grammatical
I did play. grammatical
I did sky. ungrammatical
Thus:
What I did was touch the window. grammatical
What I did was to touch the window. ungrammatical [some might say marginal]
What I did was touching the window. ungrammatical