兢兢业业 [- jīnɡ yè yè]be conscientious and do one's best; assiduous; be attentive (to one's business); be careful and conscientious; be conscientious and earnest; cautious and attentive; constantly on one's guard; do things in a careful manner; extremely watchful:
•¶兢兢业业地为国家和人民工作一辈子 work conscientiously for the nation and the people all one's life