I've leaned over backward to please you—and you haven't even said thank you!我为了让你高兴使出浑身解数，可你连声谢谢都没说！The mayor leaned over backward to avoid the appearance of nepotism.市长为了避免裙带关系的出现而走向了另一个极端。He leaned over backward to curry favour with influential officials.他极力巴结权贵。