用肉眼

• with the naked eye

例句

1. 细菌用肉眼看不见。
   Germs are invisible to the naked eye.
2. 我们不能用肉眼看到微生物。
   We can't see microscopic creature with naked eyes.
3. 我们不能用肉眼看到细菌。
   We can not see bacillus with eyes.
4. 那颗星太远，用肉眼无法看见。
   That star is too far away to see with the naked eye.