“doubtful of”可以造什么句，doubtful of造句

I was doubtful of the merits of such restrictions, but then this may have been the only way to cut off the power demand for money.

I don't think we were ever doubtful of the success of this event today, a government spokesman told reporters.

And if you do take one, you'll probably make the shop assistants feel unease, they might be doubtful of your intentions.