这里也有一个关于render 的解答，网友可以参考第二问的内容：

http://ask.yygrammar.com/q-5672.html

这里的render 意思是“使得；致使”(make)，可以接复合宾语（宾补由形容词free 充当）。

You can use render with an adjective that describes a particular state to say that someone or something is changed into that state. For example, if someone or something makes a thing harmless, you can say that they render it harmless. 

例如：

His remark rendered me speechless.

他的话使我哑口无言。

It contained so many errors as to render it worthless.

太多的错误使之变得毫无价值。