Answer:false alarm;miss
Explanation:False alarm is when police think there is something and going an extra mile to look for it ; this is better than not checking at all.
Some criminals are very good at hiding things that one may think they are not carrying anything illegal even when they are .
Precautions is better that preventions, it is always better to go an extra mile to ensure safety of the people and to ensure nothing illegal is transported into the country or is carried into the country .
A miss will occur if they let someone pass only to realise later that the person was carrying something illegal.