How does a dichotomous key you identify unknown specimens based on their traits

It helps you narrow down the possibilities based on their traits because it'll give you a wide open trait and if your specimen has that trait then it'll go on to the next one and so on eventually you'll be down to only one or two species. 

The truman doctrine was an american foreign policy whose stated purpose was to counter soviet geopolitical expansion during the cold war. it was announced to congress by president harry s. truman on march 12, 1947, and further developed on july 12, 1948, when he pledged to contain threats to greece and turkey