Communicable diseases are transmitted:

By bodily fluids, skin contact, airborne viruses, contaminated food/drinks or from insect bites.

Explanation:

Communicable diseases are contagious and can be contracted by a person in many more ways (along with those that I've listed). An example of one would be Coronavirus, it can be transferred quickly from person to person if they're not cleaned or if they haven't taken any precautions.  

the maintenance of fluid balance during exercise. author information: fluid supplementation is necessary for exercise in which fluid losses must be offset by intake to avoid the negative effects of hypohydration on health and performance.

for me i have felt invisible when i was clearly struggling,or,i made a great achievement ,and,nobody took to notice me either because they just didn't see it,or,people just turned their back on me.i can see a person being invisible by choice,or,without choice like i did.the people who are invisible by choice don't try to talk to people,don't try to make friends,and,keep to themselves.i haven't been one of those people so i couldn't give you a reason.

hope this and can i get bainliest my dude : d