It depends on the team. A team is given a certain number of roster spots, and is at liberty to have quite a few Corner Backs listed on the roster. Some use 3, some use 7.
Also bear in mind that just because someone is listed as a Wide receiver or some other position, that doesn't mean they cannot be put in for a play to play another position. We often see this in the NFL. Recently the "wildcat formation" had the quarterback lining up at the wide receiver position - and for that play the quarterback was a wide receiver.
Essentially a team can have as few or as many corner backs as they would like, within the limits of the entire team roster.
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There are seven officials on the field during a football game.
Spherical balls have no corners. The American football has 2 corners. A ball (of any shape) may be sewn together of polygons each of which has several corners (vertexes).
They can also have four. If you look at a football game, which is brightly lit from all corners of the stadium, the players will have four shadows. For three shadows, you need to be lit up from 3 corners (if you imagine a box around the person).
There are 90 minutes to a football game, plus injury time to be added.
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The average number of corners in a soccer game is around 10 to 12.
As many corners as sides.