一些微生物是肉眼看不见的。

Some microorganisms are invisible to ___the ___naked ___eye.

在晴朗的夜晚，金星用肉眼清晰可见。

The planet Venus is clearly visible with ___the ___naked ___eye on a clear night.

没有显微镜，细菌无法用肉眼观察。

Without a microscope, bacteria cannot be observed by ___the ___naked ___eye.