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》
2
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》
3
The Human Immunodeficiency Virus (HIV) targets the immune system and weakens people's surveillance and defence systems against infections and some types of cancer.