Open the brackets using the Complex Object and rewrite using inversion (a,c,e,f):
a) Mr. John said he had heard us speak about the conference. I also heard them.
b) Why did you let them play on the road?
c) He could not manage to see her brother present his report. He had left earlier. I could not see him either.
d) I want him to bring his sister with him. I have not seen her for ages.
e) He considered us to speak more languages than we really did. I also thought so. - …
f) He was watching the fire burning when I left them. His brother was also doing the same.