1. The motive for the crime was impenetrable.
    那起罪行的作案动机叫人捉摸不透。

2. Armor plate is impenetrable by ordinary bullets.
    装甲板普通子弹打不穿。

3. He is impenetrable to reason.
    跟他道理说不通。

1. 费解的：impenetrability 不能贯穿 | impenetrable 费解的 | impenetrably 无法通过地

2. impenetrable

2. 不可穿过的,难以理解的：impervious不能渗透的 | impenetrable不可穿过的,难以理解的. | implore恳求

3. impenetrable的反义词

3. 不透的：impenetability 不渗透性 | impenetrable 不透的 | imperative 强制性的

4. 不能穿透的,不可理解的：inexorable 不为所动的,坚决不变的 | impenetrable 不能穿透的,不可理解的 | incurable 不可救药的

1. 不能穿过的;刺不进的;透不过的
    If you describe something such as a barrier or a forest as impenetrable, you mean that it is impossible or very difficult to get through.

    e.g. ...the Caucasus range, an almost impenetrable barrier between Europe and Asia.
           高加索山脉,几乎难以穿越的欧亚屏障

2. 费解的;难以理解的
    If you describe something such as a book or a theory as impenetrable, you are emphasizing that it is impossible or very difficult to understand.

    e.g. His books are notoriously impenetrable.
           他的书出了名的晦涩难懂。
    e.g. ...these impenetrable poems.
           这些隐晦难懂的诗

1. impossible to understand

    e.g. impenetrable jargon

2. not admitting of penetration or passage into or through

    e.g. an impenetrable fortress
           impenetrable rain forests

3. permitting little if any light to pass through because of denseness of matter

    e.g. dense smoke
           heavy fog
           impenetrable gloom

    Synonym: denseheavy