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。

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

《柯林斯英汉双解大词典》

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。

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

youdao

这样的话，你就能化解敌人的攻势于无形。

In this way, you will be able to resolve the enemy's offensive in the invisible.

youdao