✔ 最佳答案
depends on the context....
"simple" math answer is 2
in biology, male and female, 1 plus 1 will give you 3, eventually.
in chemistry.....1 unit of water plus 1 unit of alcohol will give you about 1.75 or thereabouts (I did an experiment in 8th grade science class illustrating this)....the alcohol molecules are smaller than the water molecules, so when you mix them together, the alcohol sort of "fits in between" the water, and you get a smaller volume than 2 units....
if you mix 1 unit of something that reacts violently (chemically or otherwise) with 1 unit of something else, you will get 1 big explosion (possibly) or, as with bleach and ammonia, lots and lots of toxic fumes....not sure how you would express that mathematically!