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.

另一個使人們趨向于否定人類本性是不變的這一假設的因素是，這一概念經常被濫用，以其為擋箭牌，許多喪失人性的行為在其背后發生。

六級詞匯講解:
本句的主干是Another factor...was that...。其中現在分詞短語contributing to the tendency to...human nature作定語，修飾factor; that引導的是一個表語從句，該從句中又包含一個介詞behind+which引導的定語從句修飾shield。
tendency意為"趨向，趨勢"。如：
He had a tendency to shrink up whenever attention was focused on him.

每當人們的注意力集中在他身上時，他就會畏縮不前。

assumption意為"假設，設想"。如：
The facts proved my assumption wrong.

事實證明我的設想是錯的。

abuse意為"濫用，妄用"。如：
The president never abuses his privilege.

總統從不濫用特權。

shield意為"屏障，防護物"。如：
Dark glasses are effective shields against the glare.

墨鏡能有效地阻隔強光、保護眼睛。

commit意為"犯（錯誤，罪行等），干（壞事等）"。如：
He was accused of committing a murder.

他被指控犯了謀殺罪。

英語六級考點歸納
commit含義豐富，以下是它的一些常見用法。
表示"犯罪；犯錯"。如：
He committed murder when he was drunk.
他喝醉時犯下了殺人罪。
For one reason or another, the young girl committed suicide.

不知什么原因，那個年輕的女孩自殺了。

表示"承諾；使自己受約束，使作出保證；承擔"。如：
He refused to commit himself to any sort of promise.
他拒絕作出任何承諾。
Mary committed responsibilities to an assistant.

瑪麗承擔起助理的責任。

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

他把兒子交給他叔叔照顧。

表示"忠于（某個人、機構等）；全心全意地投入（工作、活動等）"。如：
She didn't want to commit herself to working at weekends.

她可不想把周末獻給工作。

表示"監禁，下獄；把……交付看管；判處（徒刑等）"。如：
The judge committed him to prison.
法宮判他入獄。