（6）bluish discoloration of the skin and mucous membranes caused by an excess of deoxygenated hemoglobin in the blood or a structural defect in the hemoglobin molecule: ______

Blood passes through each pump in a definite pattern. Deoxygenated blood enters the heart through the two largest veins in the body, the venae cavae. A: 血液以固定的方式流过每个泵。脱氧血通过体内最大的两条静脉即腔静脉进入心脏。 B: 血液在确定的回路里流经每个泵。脱氧血通过体内最大的两条静脉即隐静脉进入心脏。