"ask you once" is a grammatically correct phrase and can be used in written English.
It is typically used to indicate that the speaker or writer has already asked a question or requested something from the listener/reader, and is now asking again. Example: "I'll only ask you once: are you sure you want to quit your job?".
"I write to ask you once again to reconsider your position and support Labor's proposal for a royal commission into Australia's financial services industry," Shorten's letter says.
Questions and Answers Q. Can I ask you once again about criticism from current and former officers about the flow of forces to the region?
"I ask you once again to realise how unacceptable it has become," he told her. "I think it only appropriate that you should reflect on your conduct and apologise to both Stuart Gulliver and Rona Fairhead".
On Sunday, Mr. Dickerson circulated a letter for Tea Party activists around the state to forward to their members of Congress, stating, "I ask you once again to confirm to us that you are a NO vote on the president's proposal to intervene in a civil war where we have zero national interest".
When he is satisfied the instructor will hand you the try-gun and ask you once more to shoot at the whitewashed wall.
My dear grandfather told me that "they will ask you once, but they may never ask you again".
Once you click on the "Offline" link at the top of the page, the application asks you once to enable Google Gears for the Calendar.
We asked you once before, and then we asked you again: How do YOU unplug and recharge?
Or wait until they ask you - once they believe that the secret police are not listening to their small, brave acts of independence - to explain the 'Anglo-American plan' for their liberation.
"My boy, I'm going to ask you just once".
"Is this something people ask you about socially once they find out where you work?" He smiled again: "Occupational hazard".
