His leadership flaws were exposed at the critical moment.

他的领导力缺陷在关键时刻暴露无遗。

Many a time has the girl changed her answers in the test paper because she is not confident enough of herself especially when it comes to a critical moment.

这个女孩已经多次改动了试卷上的答案，因为她不够自信，尤其是在关键时刻。

It comes at a critical moment.

这正值一个关键时刻。

In the most critical moment.

就在这个最危急的关头。

This is the critical moment.

这是关键时刻。