All the time you are in doubt about the cause of your illness, you are fighting against an invisible enemy.

一直以来你都在怀疑自己的病因，你是在和一个无形的敌人斗争。

《柯林斯英汉双解大词典》

But in a less flashy way, "the Kings Speech" is about a hero, one who battles an invisible enemy that torments nearly 70 million people around the world.

从另一个角度看，“国王的演讲”的确是一部英雄戏，一个和看不见的敌人斗争的英雄。这个敌人折磨着全球近7千万人。

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H ay fever sufferers can now see the face of their invisible enemy - thanks to these Scanning Electron Microscope images of pollen grains.

由于有了电子扫描显微镜下的花粉颗粒图像，花粉症患者现在能够看到他们无形的敌人的真正面目。

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The result, they hope, will be aircraft that are lighter and easier to maintain and invisible to the enemy.

ECONOMIST: How to fly without ailerons