I have no illusions about his ability.

我对他的能力不抱任何幻想.

《简明英汉词典》

I have no illusions about his abillty.

我对他的能力不存幻想.

辞典例句

I have no illusions about his ability; he is just no good.

我对他的能力并不存在幻想; 他不怎么样.

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I have no illusions about my ability, ie I know that I am not very able.

我对自己的能力如何颇有自知之明(我知道自己的能力不很强).

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I have no illusions about my ability.

我知道自己能力有限.

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