People the Key is in the "how was it made" ;-)
It won't be a bad idea to have the answers somewhere
Hi, I love your idea to practise all kinds of transformations (and I had a look at your other worksheets, they all look fantastic!)
I have assigned this worksheet to my students, but their marks were too low (see more details at the end of this message). I have some suggestions for you if you want to improve this worksheet:
a) You could include alternative correct answers for the first part, like you did in the 5th question; for example, in #1 your answer is "She said that she could stay at home", so you could replace it with:
She said that she could stay at home / She said she could stay at home.
b) For the yes/no questions you could include part of the answer, like this:
1. She asked, "Do you like to sing"?
She asked me
Your correct answer: She asked if I liked to sing.
New correct answer: if I liked to sing.
2. Tim asked, "Did you visit London"?
Tim asked me
Your correct answer: Tim asked if I had visited London.
New correct answer: if I had visited London.
This way it is easy to change the Oi, alternating different pronouns if you like:
3. I asked, "Was your trip OK?"
I asked him/her/them/Bob/etc.
Your correct answer: I asked her if her trip had been OK / I asked him if his trip had been OK
New correct answer: if her trip had been OK (for example, depending on the pronoun or name you wrote in the prompt).
The answers of one of my best students were all correct in the statements section (but she got zero marks for that section because she didn't use "that"), and she only had two mistakes in the yes/no questions section (but she was making up the indirect objects because the context doesn't show who the question is addressed to). All her answers were correct in the commands section, and all were wrong in the wh-questions sections because she still hasn't learnt to keep the same order as in affirmative sentences.
If this looks too much trouble to you, I wouldn't mind editing your worksheet myself, if you give me permission. Then I would post here the link so that you can add it to your workbooks.