这些虫子太小了，肉眼无法看到。

These bugs are so tiny you cannot see them with ___the ___naked ___eye.

在晴朗的夜晚，这颗行星肉眼可见。

The planet is visible to ___the ___naked ___eye on a clear night.

没有显微镜，细菌无法用肉眼观察到。

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