Поставьте глаголы в Past Perfect — в первых четырех предложениях в действительном залоге, а в остальных - в страдательном:

I heard that the gentleman {to receive) a wrong answer.
Wfe did not understand what he {to say).
He told us that he {to bring) more seed,
We knew that the news {to spread).
I saw that nothing else {to make).
I knew that a mistake {to make).
We found that no letter {to receive).
Wfe saw that the text {to understand).