I don't pretend to know exactly what the party should do now.

I can't pretend to know what is going to happen.

She didn't pretend not to know what he was talking about.

He didn't pretend to know what the market would be.

He pretended not to know which problem she was talking about.

And why had they pretended to know nothing about the story last night?

I can't pretend to know much about it, but haven't you made off with rather a lot of money?

I couldn't pretend to not know what he was talking about.

He didn't pretend not to know what she was talking about.

Do you just pretend to know what you're talking about?