头等

firstclass; topnotch; prime; foremost; premier; toptier

重要

important; great; significant; major; crucial; critical; principal; substantial; fundamental; consequential; material; vital; salient; importance; consequence; significance; weightiness; prominence; emphasize; count; prioritize; highlight the importance of

任务

task; mission; assignment; duty; role; job; charge; errand; undertaking; responsibility; sortie; labour; proposition; detail; exercise