Despite anything the science of medicine may have achieved, the immune system is our main defence against disease.

不管医疗科学已取得了什么样的进步，免疫系统仍是我们抵抗疾病的主要防御手段。

《柯林斯英汉双解大词典》

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The most serious deficiency in NATO's air defence is the lack of an identification system to distinguish friend from foe.

北约防空的最大缺陷就是缺乏能够辨认敌友的识别系统。

《柯林斯英汉双解大词典》

Russia appears close to agreeing a deal to revise the anti-ballistic missile treaty - lifting its objections to an American system of missile defence.

BBC: Shanghai showcase

When the US embarked in the 1950s on the construction of the 42, 795-mile National System of Interstate and Defence Highways, Americans applauded.

BBC: Killer on the road: why mass murderers haunt US highways

There is also a more subtle defence of the American political system: the hazing defence.

ECONOMIST: A hard day’s night | The