The smile faded; he was obviously wondering if I was mentally competent.

笑意逐渐消失了；他显然是想知道我的智力是不是能够胜任这个问题。

This document has to be drafted and signed while they are still mentally competent.

该文件必须在他们仍具有精神能力时起草和签署。

Obviously, she is not mentally competent enough to handle her finances.

她现在精神状态明显不能够正确地处理她的财务。

Are you mentally competent and under no duress at this time?

你现在是否心智正常且没有受到监禁？

We're talking about whether someone is mentally competent – whether they can think and behave rationally and logically.

我们谈论的是一个人是否具有心理能力——他们是否能够理性和合乎逻辑地思考和行动。

They somehow lack, or don't have, what they need in order to be completely mentally competent or " sane, " we would say.

他们不知何故缺乏，或没有，我们会说，他们需要的东西才能完全具有精神能力或“理智” 。