1+1=?
the answer may be is 1, 2 or 3
why is that so?

(1.)1 human + 1 human = ? human
1 woman + 1 man will give birth...
so the answer can be <3>

(2.)1 apple + 1 apple = ? apple
1 + 1 = 2
so the answer is <2>

(3.)1 boy + 1 apple = ?
the boy had eaten the apple...
so, there are only <1> boy
the answer is 1...