在老师的指导之下，他的成绩提高了不少。

Zài lǎoshī de zhǐdǎo zhī xià, tā de chéngjì tígāo le bù shǎo.

Under the teacher's guidance, his grades improved quite a lot.

大雪之下，整个城市变得安静极了。

Dà xuě zhī xià, zhěnggè chéngshì biàn de ānjìng jí le.

Under the heavy snow, the entire city became extremely quiet.

在巨大的压力之下，他依然没有放弃。

Zài jùdà de yālì zhī xià, tā yīrán méiyǒu fàngqì.

Under enormous pressure, he still did not give up.