AIDS is a disease that leaves a person defenceless against infection and illnesses.

艾滋病是一种可使人丧失抵抗力以及产生病变的严重疾病。

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Although seemingly defenceless, it is capable of simply flinging itself from its perch, curling up into a ball and bouncing off boulders and down steep slopes to safety.

虽然看上去无法自卫，它却可以从栖息的高位简单的将自己投掷出去，卷成一团在大卵石之间弹来弹去滚下险峻的斜坡抵达安全地带。

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"It would have been a smorgasbord," said Head. "Hundreds or thousands of defenceless baby sauropods could have supported an ecosystem of predators during the hatching season."

Head博士提到：他们就如一顿美味的自助餐一样，在孵化季节成千上万的毫无防御能力的晰脚类恐龙幼仔支撑了整个食肉恐龙的生物食物链。

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"My judgement is that it would be foolish to leave Britain defenceless against a continuing, and growing, nuclear threat, " he said.

BBC: UK must keep Trident nuclear deterrent - David Cameron

At Manchester Crown Court, prosecutor Simon Phillips QC said Mr Rigby made a "wicked attack on a defenceless child".

BBC: Rio Smedley

"May peace spring up for the people of Syria, deeply wounded and divided by a conflict that does not spare even the defenceless and reaps innocent victims, " he said.

BBC: Pope Benedict in Christmas plea for Syria solution