Questions

There are approximately 6 trillion miles in a light-year, so the distance we need to go is 6 trillion miles / light-year times. 4 light-years is equal to 24 trillion miles. So, this whole would take 1.2 billion hours. There are 24 hours a day and 365.25 days per year, so this time in years is 137 thousand years.

A Disease which spreads by contact are Contagious.

Infectious diseases : These are caused by microscopic germs such as bacteria or viruses that get into the body and cause problems. Some but not all infectious diseases spread directly from one person to another. Infectious diseases that spread from person to person are said to be contagious. Some infections spread to people from an animal or insect, but are not contagious from another human. 

Contagious diseases such as the flu, colds, or strep throat spread from person to person in several ways. One way is through direct physical contact, like touching or kissing a person who has the infection. Another way is when an infectious microbe travels through the air after someone nearby sneezes or coughs.

Fatal Diseases : Diseases leading to failure or disaster.

Incurable Diseases : Diseases of a sick person not able to be cured.

Excessive use of nitrate including manure may be responsible forthe presence of toxic substance in groundwater. Phosphate can also enter the groundwater via excessive use of fertilizers. High application rates of nitrogen containing fertilizers combined with the high-water solubility of nitrate, leads to increased runoff into surface water as well as leaching into groundwater, thereby causing groundwater pollution.

Only a fraction of the nitrogen-based fertilizers, is converted to produce and other plant matter. Nitrate pollution in groundwater comes from pit latrines, it can cause blue baby syndrome.

When both sides have won the same number of points then: when each side has won one, or two, points, the score is described as "15-all" and "30-all" (or "15-up" and "30-up"), respectively.

However, if each player has won three points, the score is called as "deuce", not "40–all". From that point on in the game, whenever the score is tied, it is described as "deuce", regardless of how many points have been played.

Stamps are what travel around the worldstaying in one spot. Slippers and walking stick can also travel around the world but they will not stay at one spot. So they are eliminated.