問題詳情

45. In order for blood to always flow unidirectionally through a closed circulatorysystem, the_______.
(A) blood vessels farthest from the heart must have valves
(B) capillaries must have a thick endothelium
(C) arteries must be elastic
(D) pressure in all vessels must be equal

參考答案

答案：[無官方正解]
難度：計算中-1
書單：沒有書單，新增