Questions

Romans (753 BC - AD 410) began public health and sanitation systems.

Romans established the first public health and sanitation systems by building sewers and aqueducts.

They also treated diseases with diet, exercise and meditation.

The required number is SEVEN.

If you remove  S, it becomes EVEN.

The main difference lies in the motive of the two parties. The main motive of the hedger is to hedge(minimize) the risk from the occurence of some events. 

The motive of the speculator is to gamble in the market in order to make the profit by buying/selling the derivative products.

Oxygen is transported throughout the body via hemoglobin in the red blood cells. Hence, most of the oxygen transported by the blood is bounded to hemoglobin.

Secondary storage therefore needed because it is non-volatile, meaning it retains its contents without the need for a power supply. It also has the large storage capacity needed to store the operating system and all the programs and files needed by a modern computer system.

China blocked wikipedia in all languages recently in May 2019.

Assessing opportunity cost involves making choices and dealing with consequences.