This alone demonstrates...

【翻译】仅这一件事就说明了......

alone是副词，意为“仅仅，只有，单单”。但在意思上是修饰前面的名词。又如：

This alone made our nine-day trip worthwhile. 光这件事我们9天的旅行就非常值得。

This alone stamps him as a swindler. 仅这一件事就表明他是一个骗子。

This alone would justify its inclusion amongst Hawthorne's major works. 凭着这一点它就有资格列入霍桑的重要作品。

This alone will convince ordinary Americans that he is on top of the issue. 这足以令美国百姓相信，局面在他的控制之下。

This alone automatically makes you the lucky dog. 单单这个就足以使你成为幸运儿。