You'll look taller if you stand up straight.

站直身子，你会显得高些。

《牛津词典》

If you stand up straight, you'll give an impression of self-confidence, even if you're quaking in your boots.

只要你站直了，就会给人一种自信的印象，哪怕你正紧张得发抖。

《柯林斯英汉双解大词典》

Using proper body language will help, stand up straight, make eye contact with people, and smile!

使用适当的肢体语言会有所帮助，站直，与人进行眼神交流，微笑！

youdao

It's not really hard. You just make your bed neat, remember to stand up straight, and always answer every question with "Yes, Drill Sergeant."

VOA: standard.other

I mean, I can't stand up straight.

我是说，我都站不直了。

Let's 实战 - SpeakingMax英语口语达人

Getting this wobbly droid simply to stand up straight is a challenge, but Blackwell is optimistic.

FORBES: Magazine Article

Stand up straight, speak clearly and concisely, make eye contact and keep breathing.

FORBES: 4 Staggering Women's Beliefs About Competition!

And you all always thank us, but we stand here, stand up straight, breathing in and out every day because of your support.

WHITEHOUSE: Remarks by the First Lady at a Campaign Event -- La Jolla, CA