Poor nutrition and lack of sleep.
Relationships must be maintained. because if their not maintained it could turn into a bad relation ship that could mentally and physically hurt yourself or be hurted. and that takes work from each partner or friends whatever relationship it is.
The parts of the eye that are most important when it comes to focusing light so we can see a perfect image would be the cornea and the retina. T<span>he retina forms the entire curved inside of the eyeball and is lined with two types of light-sensitive cells, the rods which are sensitive to light of low intensity but not to colors, and the cones which are sensitive to colors. Hope this answer helps.</span>