e.g.
x+1 = 2 if and only if x = 1
點解唔可以寫成x+1 = 2 only if x = 1?
更新1:
我識分if同if and only if 但我唔明點解唔可以就咁寫做only if,only if已經包含晒if and only if 既meaning 是不是因為上面的statement可以分拆做 1.if x=1 then x+1=2 2.x+1 = 2 only if x = 1 咁點解1唔可以寫做only if x=1 then x+1 = 2?