任务

main/primary task

combat mission

overwhelming task; task taking precedence over all others

special assignment

task of primary importance

urgent task

arduous/daunting/formidable task; heavy responsibilities

work/study assignments

long-duration/long-term mission

carry out/discharge one's mission; be on a mission; carry out/perform/undertake a task

wrap up/do one's task; accomplish/complete/fulfil an assignment; complete/finish a task; execute/fulfil one's mission

accept an assignment/mission/task

allot assignments; assign (sb) a mission; assign a task (to sb)

accept/take on a task; shoulder/undertake a task; be engaged in a task

give sb a task; task sb (with sth); brief sb on a job