The effect has proved hard to reproduce.

这种效果经证实很难再现。

I shall not try to reproduce the policemen's English.

我不应该试图重复这个警察说的英语。

We are grateful to you for permission to reproduce this article.

我们很感激您允许我们复印这篇文章。

If we can reproduce the form we have shown in the last couple of months we will be successful.

如果我们能够重现上两个月表现出来的状态，我们就会成功。

a society where women are defined by their ability to reproduce.

一个以生育能力来定位妇女角色的社会。

We are reproducing ourselves at such a rate that our numbers threaten the ecology of the planet.

我们繁衍得如此之快，以至于人口数量威胁到了地球的生态系统。