A substitution , is when a player that is on the field, switches with a player that is on the sidelines, so that players can all get to play.
On a corner kick or on the other teams throws.
None at all! Only for injury or substitution normally! GHERKIN
The linesmen have a flag each. They use these to indicate, a foul, a throw in, a corner, an offside, a goal kick or a substitution.
There is no requirement that time be added for a substitution. If the substitution takes longer than the referee thinks it should, he will add that extra time on to the end of the half. Typically, no more than 15 to 30 seconds will be added for a substitution, unless a player is cautioned for delaying the start or restart of play.
At youth levels of soccer, players generally line up at the midfield line and yell "sub ref" when they want to enter the field of play. At higher levels of soccer. A fourth official will communicate between the player and referee crew regarding a substitution. The assistant referees will signal with their flags above their head and the referee will give permission for the substitution to take place.
I can give you several sentences.Use that ingredient as a substitution for the one you don't have.He is going in as a substitution for the quarterback.This is a substitution for the real thing.Margarine could be used as a substitution.
Very effective, since a team is only allowed 3 substitutions, putting in 3 provides fresh energy.
There is no substitution for eggs when cooking
marginal rate of substitution