1 something new and difficult that forces you to make a lot of effort 艰巨的新任务: I'm finding my new job an exciting challenge. 我觉得这个新工作令人兴奋而具有挑战性。The company will have to face many challengesin the coming months. 在未来几个月里，公司得面临许多艰巨任务。How will this government meet the challenge of rising unemployment? 这个政府将怎样处理失业率不断上升的难题？

2 a challenge (to sb) (to do sth) an invitation from sb to fight, play, argue, etc against him/her （为比试实力而发出的）挑战: The Prime Minister should accept our challenge and call a new election now. 首相应该接受我们的挑战，实时重新举行选举。