Hypertension is the medical term for persistent and sustained high blood pressure. It is one of the most (51) forms of heart disease. An understanding of blood pressure in (52) , healthy individuals is necessary in order to understand hypertension.Blood pressure is simply the force (53) against the walls of the body’s arteries (血管) as blood flows through. The force, produced primarily by the pumping (54) of the heart, is essential for the (55) of the blood and its life-supporting nutrients(营养) to all parts of the body. Every time the heart (56) , called a systole, blood pressure increases. When the heart relaxes (57) beats(diastole), the pressure decreases. The normal systolic pressure of a person at vest is between 100 to 140, and the normal diastole is 60 to 90. Blood-pressure readings are expressed by both (58) , with the systolic over the diastolic: for example, 140/90.As these ranges suggest, there is a wide (59) of blood pressure for healthy people. Also, blood pressure (60) for healthy people during different times of the day and under different. (61) . It is lower when an individual is asleep than when he is excited or exerting himself physically. Therefore, a single blood-pressure reading above 140/90 does not (62) abnormality. When the pressure is continuously (63) , a person is considered to be suffering from hypertension.Hypertension is a stealthy(隐秘的) problem: a physician can discover it easily enough, but not a patient. (64) elevations, for example, may produce headaches, dizziness, fatigue, and weakness. But the patient is not likely to (65) these symptoms as having any other source than the increased elevation. 56()
A. condenses
B. compresses
C. concentrates
D. contracts
在美国出生的正常的婴儿在3个月大时平均体重在12—14磅之间。因此,如果一个3个月大的小孩体重只有10磅,那么这个小孩的体重增长低于美国平均水平。 以下哪一项指出了上面推理中的一处缺陷( )
A. 体重只是正常婴儿成长的一项指标。
B. 一个正常的小孩出生时体重达到10磅是有可能的。
C. 短语“低于平均水平”并不一定意味着不够。
D. 平均体重增长与平均体重并不相同。