Please sit up straight in your chair.

请你在椅子上坐好。

Make sure to sit up straight when you are driving.

当你开车时，一定要坐好。

The teacher asked us to sit up straight in class.

老师要求我们在课堂上坐好。

Xiao Ming always forgets to sit up straight, so his back often hurts.

小明总是忘记坐好，所以他的背经常疼。

The doctor advised me to sit up straight every day to protect my spine.

医生建议我每天坐好，以保护我的脊椎。

If you tell me, Sit up straight, now I have to use all of my brain to do just that.

如果你告诉我：“坐好”，现在我得花所有脑力去只做那件事。

Sit up ; sit up straight.

坐起来；坐直；熬夜。

T slouch, sit up straight

别耷拉着，坐直了

Don't scrunch up like that. Sit up straight.

不要那样缩头缩脑的，坐端正。

Sit up straight child, you look like a slopped pear.

坐直了，孩子，你看上去就像是一只烂梨。