Hi! I just want someone to check if these answers are correct. Thank you! You guys are really helpful!

Complete the sentences at (b) so that they give the same meaning as the sentences at (a):
a. He arrived at the party at 8. She left at 7.45.
b. When he arrived at the party at 8, she had already left.
a. I rewarded him with $20 for finding my wallet.
b. He was rewarded $20 by me, for finding my wallet
a. “Who is Diana?” he asked.
b. He asked me who Diana is..... or would it be "He asked who Diana
was" not sure about putting "
me" too
a. It would be foolish to disagree over it.
b. Let’s not be foolish and disagree over it
a. He can only pass if he studies harder.
b. Studying harder is the only way he can pass.