Sentence examples for instructions is doubtful from inspiring English sources

Orthodontic patients are often at high risk of developing dental caries during orthodontic treatment, especially when their compliance to oral hygiene instructions is doubtful [ 30].

(On the other issue considered, the court ruled that prejudice due to deficient representation in respect of jury instruction was "doubtful", but even if it had been deficient, other evidence of guilt corroborating the conviction made it unlikely that a change of jury instruction would have made any difference).

That much is doubtful.

Mr Piketty is doubtful.

Danny Welbeck (muscle) is doubtful.

On that Harari is doubtful.

Fontana is doubtful.

Bleasdale is doubtful.

But Twagirimana is doubtful.

However it is doubtful.

A glutton, Antony is doubtful.