Question

It is okay for a racewalker briefly to have both feet off the ground at one time.

Answer 1

False

You must keep at least one foot on the ground at all times. And your front, supporting leg must stay completely straight from the moment it touches the ground until your center of gravity passes over it. Failure to do so is called a "lifting infraction." 

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Answer 2

False race walking means you must have one on the ground