Using "?:" after a question

I find myself using the dual punctuation marks "?:" when I want to say "I have a question about the thing that follows". For example:

Is it possible for the following sentence to be translated into French?:
"Hello, nice to see you."

Is using "?:" incorrect? If so, what would be the correct way to do this? Which would take precedence: the colon, or the question mark?

Two such punctuation marks together are generally best avoided. You can instead insert a blank line to separate the question from the example, like this:

Is it possible for the following sentence to be translated into French?

"Hello, nice to see you."

Better still might be to write:

Is it possible for "Hello, nice to see you" to be translated into French?