The phrase "a main task to" is correct and usable in written English.
It can be used when introducing a primary objective or responsibility in a given context.
Example: "The project manager outlined a main task to ensure the team meets the deadline."
Alternatives: "a primary objective to" or "a key responsibility to".
But most writers on the crime suggest Mr Biggs played a peripheral and unsuccessful role in it.He failed in his main task, to recruit a train driver to the gang.
A main task has been to convince Minnesotans that he is one of them—he grew up there, but spent much of his adult life in New York.
Himmler saw a main task of the SS to be that of "acting as the vanguard in overcoming Christianity and restoring a 'Germanic' way of living" as part of perparations for the coming conflict between "humans and subhumans".
Moreover, GPs often interpret symptoms in the context of consequences and it is a main task for primary care to identify serious disease as quickly as possible because delay in diagnosis may affect prognosis [ 54].
A main task of behavioral scientists is to develop or adapt existing tests to generate valid and sensitive test paradigms applicable to most commonly used model animals in addition to pigs and/or suitable for behavioral characterization (phenotyping).
A main task for the mediator is to manage these emotions.
In everyday listening environments, a main task for our auditory system is to follow one out of multiple speakers talking simultaneously.
A main task in writing this book was to sort out the grain from the chaff.
A main task of the INSPIRE programme is to enable interoperability and, when feasible, harmonisation of spatial data sets and services within Europe.
Controlling humidity within the structure was a main task for the designers, Hick explained.
