1. 过高估计（数量、重要性等）
    If you say that someone overestimates something, you mean that they think it is greater in amount or importance than it really is.

    e.g. With hindsight, he was overestimating their desire for peace.
           事后看来，他高估了他们对和平的渴望。

2. 再怎么估量（都不为过）
    If you say that something cannot be overestimated, you are emphasizing that you think it is very important.

    e.g. The importance of participating in the life of the country cannot be overestimated...
           参与国家生活的重要性再怎么说都不为过。
    e.g. It is hard to overestimate the potential gains from this process.
           这一工艺的潜在收益不可估量。

3. 过高评价（某人）
    If you overestimate someone, you think that they have more of a skill or quality than they really have.

    e.g. I think you overestimate me, Fred.
           我认为你高估我了，弗雷德。