The adobe dwellings(土坯房) 61.________(build) by the Pueblo Indians of the American Southwest are admired by even 62.________ most modern of architects and engineers. In addition to their simple beauty, what makes the adobe dwellings admirable is their 63.________(able) to “air condition” a house without 64.________(use)electric equipment.Walls made of adobe take in the heat from the sun on hot days and give out that heat 65.________(slow) during cool nights，thus warming the house. When a new day breaks, the walls have given up their heat and are now cold enough 66.________(cool) the house during the hot day; 67.________ the same time, they warm up again for the night. This cycle 68.________ (go) day after day: The walls warm up during the day and cool off during the night and are thus always a timely offset(抵消) for the outside temperatures. As 69.________(nature) architects, the Pueblo Indians figured out exactly 70.________thick the adobe walls needed to be to make the cycle work on most days.