Are these examples of cleft sentences correct?

1) emphatic "A noun clause can be a subject of a verb"
What Billy did shocked his friends.
-> It is What Billy did which/ that shocked his friends.

2) emphatic "A noun clause can be an object of a verb"
Billy's friends didn't know that he couldn't swim.
-> It is that he couldn't swim which/ that Billy's friends didn't know,

This message has been edited. Last edited by: Rachel, Moderator,

Sentence 1) can appear in the two ways you have showed us:

What Billy did shocked his friends.

and

It was what Billy did THAT (not 'which') shocked his friends.

Sentence 2 can be like this:

Billy's friends didn't know that he couldn't swim.

Your second example in sentence 2) is not quite correct. We usually don't start the noun clause after "it is" with "that"; we'd use "the fact that...."

It was the fact that he couldn't swim that Billy's friends didn't know.
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Vien, your original posting was very long. I have broken it up into smaller parts and will post the other sentences separately within the next 24 hours.

Rachel