The ova are suspended in a liquid, invisible to the naked eye.

肉眼不可见的ova被混悬在液体中， “是没有味道，而且也感觉不到的”， Weinstock博士说。

youdao

The microscope enables us to see organisms invisible to the naked eye.

显微镜使我们能看到肉眼看不见的有机组织。

youdao

The card produced by the University of Glasgow, said to be the smallest in the world, is invisible to the naked eye.

这种卡产自（英国）格拉斯哥大学，据说是世界是最小的，肉眼看不见。

youdao

The proton aurora is invisible to the naked eye and has never been viewed from space.

BBC: Atmosphere Nasa

The samples revealed "no-see-um" gold, invisible to the naked eye but detectable via assay.

FORBES: Virtual Gold

Fungi, bacteria and viruses are largely invisible to the naked eye but not to the naked body.

FORBES: The Best and Worst of Times: Killer Vegetables, Plunging Markets, Infinite Nature