兢兢业业
[词典] be conscientious and do one's best; assiduous; be attentive (to one's business); be careful and conscientious;
[例句]他更加谨小慎微，兢兢业业，以尽力取信讨好其上司。
He was even more cautious than ever, and did his utmost to win the trust and favour of the superior.