GRE Text Completion: JiJing 1373-GRE填空机经1373题 - G8HH877BRFEINM5IA

The circulation of the blood makes human adaptability to the ____________ conditions of life, such as fluctuating atmospheric pressure, level of physical activity, and diet, possible. A. inveterate B. dynamic C. timorous D. cowed E. turgid F. oscillating