315.Another factor contributing to the tendency to deny the assumption of a fixed human nature was that the concept has so often been abused as a shield behind which the most inhuman acts are committed.

另一个使人们趋向于否定人类本性是不变的这一假设的因素是，这一概念经常被滥用，以其为挡箭牌，许多丧失人性的行为在其背后发生。

六级词汇讲解:
本句的主干是Another factor...was that...。其中现在分词短语contributing to the tendency to...human nature作定语，修饰factor; that引导的是一个表语从句，该从句中又包含一个介词behind+which引导的定语从句修饰shield。
tendency意为"趋向，趋势"。如：
He had a tendency to shrink up whenever attention was focused on him.

每当人们的注意力集中在他身上时，他就会畏缩不前。

assumption意为"假设，设想"。如：
The facts proved my assumption wrong.

事实证明我的设想是错的。

abuse意为"滥用，妄用"。如：
The president never abuses his privilege.

总统从不滥用特权。

shield意为"屏障，防护物"。如：
Dark glasses are effective shields against the glare.

墨镜能有效地阻隔强光、保护眼睛。

commit意为"犯（错误，罪行等），干（坏事等）"。如：
He was accused of committing a murder.

他被指控犯了谋杀罪。

英语六级考点归纳
commit含义丰富，以下是它的一些常见用法。
表示"犯罪；犯错"。如：
He committed murder when he was drunk.
他喝醉时犯下了杀人罪。
For one reason or another, the young girl committed suicide.

不知什么原因，那个年轻的女孩自杀了。

表示"承诺；使自己受约束，使作出保证；承担"。如：
He refused to commit himself to any sort of promise.
他拒绝作出任何承诺。
Mary committed responsibilities to an assistant.

玛丽承担起助理的责任。

表示"把……托付给；委托；委任"。如：
He committed his son to the care of his uncle.

他把儿子交给他叔叔照顾。

表示"忠于（某个人、机构等）；全心全意地投入（工作、活动等）"。如：
She didn't want to commit herself to working at weekends.

她可不想把周末献给工作。

表示"监禁，下狱；把……交付看管；判处（徒刑等）"。如：
The judge committed him to prison.
法宫判他入狱。