英语问题Tow fathers and two sons go to take a picture. When they

Because they are grandfather,father and son.
因为是爷爷、爸爸和儿子（明白了吧） :)

Yeah I know!
Because they are one grandfather,one father and one son. The grandfather is the father's father.The father is the son's father.And the son is the father's son.The father is the grandfather's son. So there are tow fathers and two sons.

呵呵 楼上都已经说了 就是祖孙三人。爷爷是爸爸的爸爸，爸爸是儿子的爸爸~