That-clauses

No indirect object.

What do you and your best friend agree about?

We agree that Mel Gibson is the best actor in the world.

How did the lecturer answer your question about space technology in the future?

What did you conclude from the research on Martian soil?

What do most children know without their parents telling them?

What did you notice about the 'original' Monet painting in the Beijing art museum?

What did you realize after you had been on the subway for 10 minutes?

What did you think about the movie?

To required with indirect object

What did the criminal admit to after the police interrogated him?

The criminal admitted (to the police) that he stole the painting.

What did the lady mention about her possible plans this weekend?

What did the tour guide point out about Sukhbaatar Square?

What did Isaac Newton prove?

Indirect object required

What did the doctor assure the patient about?

The doctor assured him that he was going to live at least 20 more years.

What did the religious man convince you of?

What did the president notify you (all) about?

What did one look at the calendar remind you of?

Indirect object optional

What did the MC promise about tonight's show?

The master of ceremonies promised (the audience) that tonight's show would be the best.

What did the results of the survey show?

What has your teacher taught you about writing?

What did the sign warn the swimmers about?

What did the man write before he committed suicide?