1 List the features of the gaseous exchange surface in humans.

Explanation:

1. They are moist to prevent the cells from drying and to allow gasses to dissolve.

2. They have high concentration gradient, maintained by the movement of air and blood.

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.