if in doubt used when advising someone what to do if they are uncertain about something 当某人对某事不确定时，建议他做某事时就用这个短语;翻译为“如果不确定的话，如果拿不定注意的话” A: When I go to the shop, should I lock the door, or leave it open? 当我去买东西的时候，我应该锁门，还是让门开着? B: If in doubt, l