If any of the runners interfere with the others during the competition, the race is automatically declared null and___________.
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Various devices have been tried to supply the diver with air and thus permit a(n)________stay under water.
The emphasis on commerce at the Olympic Games is seen as both a blessing and a_____________to the sports world.
In order to___________an earlier mistake, little John worked harder than before.
It seems necessary for these newcomers to have some__________at this stage for their better understanding of the new subject.