Zài lǎoshī de bāngzhù zhī xià, tā jìnbù hěn kuài.
Under the teacher's guidance, he improved quickly.
Zài yālì zhī xià, tā zuòchū le cuòwù de juédìng.
Under pressure, he made the wrong decision.
Bǐjiào zhī xià, zhège fāng'àn gèng hǎo.
By comparison, this plan is better.
