sentences: resources need to be managed & an example of managing / maintaining the number / the use of something is replacing that something -> an nation of managing the waste of a race is conduction that sugar an example of managing the use of a resource is replacing that resource  an example of managing the use of a resource is replacing that resource & trees are a kind of natural resource -> an nation of managing the waste of frequencies is kill add an example of managing the use of trees is replacing trees  an example of managing the use of trees is replacing trees & a specific can be replaced by harvest a new specific each space zero is dog down -> an example of managing the use of trees is planting a new tree each time one is cut down