Read the passage below and then answer the questions that follow.Judging by weight alone, we humans are made mostly of water. This water,which is salty, accounts for between 60 to 70 per cent of the body’s weight –about 45 kilograms in the average adult male. Even our seemingly solid bonesare 20 percent water, while our blood plasma is 95 percent water. Therefore,the fluid inside the human body can be referred to as a salty inland sea.The inland sea is the watery environment that the first groping organismcarried with it when it crept out of the warm life-nurturing oceans on to the land500 million years ago. This sea flows through the blood vessels and all thebody’s ducts, however tiny. It laps every cell wall and fills every cell. No part ofthe body could survive without it.It saves us quite literally, from being consumed in our fires. Chemical activitygoing on everywhere in the body all the time, plus the heat of muscular activitywhen we are doing physical work or exercising, produce enough heat to burn usup. However, the water that bathes the cells and seeps through the tissuesabsorbs the excess heat as fast as it is produced.The sea within us is also a shock absorber. There is a fluid bath that sheltersthe brain from shock. Similarly, our bones and joints, organs and nerves arecushioned against the thousand jars the body must take from the solid world inwhich we live. Without water, the pounding of heels on the pavement or of ahammer in the hand would probably be almost unbearable.One of the best of solvents, the water in the human body carries manyvaluable chemicals in solution and many more in suspension. Its ability to holdsodium and potassium in solution, for example, is indispensable to thetransmitting of electrical impulse that activate muscles and nerves.The body’s water supply, like its food supply, needs to be constantlyreplenished. Normally, we drink in a day about one and a half litres of wateralone of other beverages. We get another one litre of fluid in our foods for, drythough they may seem, most food (even meats) are as watery as we ourselvesare. The body’s total daily output is about one and a half litres of urine, plusabout one litre of water lost in vaporization which provides cooling by water ofthe lungs and skin.