1. 排除；杜绝；防止
    If something precludes an event or action, it prevents the event or action from happening.

    e.g. At 84, John feels his age precludes too much travel...
           84岁的约翰感到自己年事已高，不能进行太多的旅行。
    e.g. He would rebuff enquiries in such a way as to preclude any further discussion.
           他会断然拒绝询问，使得无法进行进一步的讨论。

2. 阻止；妨碍
    If something precludes you from doing something or going somewhere, it prevents you from doing it or going there.

    e.g. A constitutional amendment precludes any president from serving more than two terms...
           一项宪法修正案使得任何总统的任职不得超过两届。
    e.g. In some cases poor English precluded them from ever finding a job.
           英语不好有时会让他们找不到工作。