"Please check one more time."

Translation: 请再检查一次。

[oLs_st]

请再一次检查.. why is this not correct?

[KX3.]

The sentence is hanging, it needs something at the end to complete it. It'd be correct if, for example, a noun were to follow, e.g. 请再一次检查行李/考卷, but is still less commonly used.

[RobinThor]

What do you mean? The sentence is hanging?

[kuyaC]

Why isn't 请在检查 enough?

[phanter]

Can we say 请检查再一次？

[KX3.]

You can say 请检查（再）多一次, the 再 in the bracket is mainly for colloquial usage only.

[1b4q4]

Why do we need 再 here?

[KX3.]

Without it, 请检查一次 = Please check once.

[CharlesE780046]

Is 青还检查一次 possible?

[KX3.]

青 = green，请 = please. Pay attention to the 部首（radicals）, they often give a clue as to the nature of the word. In this case, if you ask someone to help you or to do something, you use your mouth to speak so the radical 言字旁 where 言 refers to speech in general is present. Other words include 诉说、讨论、（言）讲等 for narrate/describe, discuss/辩论（debate）, speech/giving a speech and so on.

[IanMcFarla17]

This the third time in this lesson that the correct answer has been marked wrong. It mystifies me how this can be such a constant problem.