The "eight glasses a day" rule presumes 8-oz glasses:
8 x 8 = 64 oz = 2 quarts
1 quart = 946 ml x 2 = 1892 ml
So you should drink 3.784 of those 500ml bottles of water.
Looked at another way, each of those 8oz glasses of water holds 236.5 ml, so if you drink all four 500ml bottles of water, you're drinking a little more than 8 1/2 glasses of water.
Looked at a third way, if you measure an extra half-ounce of water into each of your eight glasses, you're up to four 500ml bottles.
Not sure it depends on the healthiness of the person
Someone who is always there for you and never leaves your side
Carbohydrates are pretty much the main source of energy for the body, so a diet that is rich in dairy but lacking in carbohydrates is probably the correct answer.