whether and if

  • In reported questions, we can use both whether and if.
      I’m not sure whether/if I ‘II have time.
      I asked whether/if she had any letters for me.
      We prefer whether before or, especially in a formal style.
      Let me know whether you can come or not.
      ( … if … is possible in an informal style.)
  • After discuss, only whether is possible.
      We discussed whether we should close the shop.
      (NOT We discussed if . . .)