"doubtless about" is a grammatically correct phrase that can be used in written English.
It is typically used to convey certainty or assurance about something. Here is an example sentence: "Doubtless about their victory, the team confidently marched onto the field."
Her body was immobile, apart from her eyelids, beneath which her eyes were doubtless moving about, as though they couldn't get used to not doing at night what they did during the day.
The latter was something of a hindrance as he weighed his vegetables and trundled his cart about; doubtless the case contained classified documents from the War Office.
He's doubtless joking about the rollercoaster itself which, although charming, is about as hair-raising as its name – the Scenic Railway – suggests.
And he was doubtless upset about the public nature of the divorce.
Mr. Milosevic is doubtless thinking about his own political survival, always his first concern.
Like Brown and Tony Blair in 2005, David Cameron and his government doubtless care about these issues.
There are huge numbers of mobile growth that you've seen in [INAUDIBLE] presentation, or you have doubtless heard about.
Mac Stipanovich, a Republican strategist in Tallahassee, said that while Governor Bush was doubtless thinking about returning the family favor in 2004, his primary motivation was improving Floridians' lives.
This scene – the acclaimed writer in his rock'n'roll lair discussing his latest work with a member of the international press – is doubtless one about which the young Knausgaard dreamed.
Tunisians did not go to the polls to choose higher or lower taxes, stronger or weaker unions, better integration of the informal economy or an elimination of it, though they doubtless care about these things.
