I just wanted to know your opinion about a very simple idea.

There was no need for him to ask; he already knew her opinion on the matter.

"He always wanted to know my opinion on everything," she said.

These days, he generally doesn't want to know my opinion.

"The people here are involved and make their opinions known," she said.

"You already know my opinion on continued study," she said.

"You don't seem to care if she knows your opinion."

I just want to know your opinion about this possibility.

You want to know my opinion, he wasn't no accident.

"And it would interest me to know your opinion regarding them."