Asking for Information

Aren't you forgetting about X?

Be that as it may, what about X?

Do you happen to know about X?

Do you seriously believe X?

Do you seriously believe that X?

I have a question about X.

I'm not sure I understand.

Tell me more about X?

The question still remains as to X.

What about X?

What's up?

Wouldn't that be related to X?