翻译英语“请站直，因为站直的时候测量的结果才准确”

Please stand up straight, we can't get the right messurements if you don't stand up straight.

Please stand straight ,for only by this can you get an accurate measuring figure (on your height).
谢谢3楼指正！

Please stand staight, and only then can we get the accurate measurement!
上面的翻译单词有误！