Hypertension is the medical term for
persistent and sustained high blood pressure. It is one of the most
{{U}}(51) {{/U}} forms of heart disease. An understanding of blood
pressure in {{U}}(52) {{/U}}, healthy individuals is necessary in order
to understand hypertension. Blood pressure is simply the
force {{U}}(53) {{/U}} against the walls of the body's arteries (血管) as
blood flows through. The force, produced primarily by the pumping {{U}}(54)
{{/U}} of the heart, is essential for the {{U}}(55) {{/U}} of the
blood and its life-supporting nutrients(营养) to all parts of the body. Every time
the heart {{U}}(56) {{/U}}, called a systole, blood pressure increases.
When the heart relaxes {{U}}(57) {{/U}} 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 {{U}}(58) {{/U}}, with the systolic over the diastolic: for
example, 140/90. As these ranges suggest, there is a wide
{{U}}(59) {{/U}} of blood pressure for healthy people. Also, blood
pressure {{U}}(60) {{/U}} for healthy people during different times of
the day and under different. {{U}}(61) {{/U}}. 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 {{U}}(62)
{{/U}} abnormality. When the pressure is continuously {{U}}(63)
{{/U}}, 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. {{U}}(64) {{/U}} elevations, for
example, may produce headaches, dizziness, fatigue, and weakness. But the
patient is not likely to {{U}}(65) {{/U}}these symptoms as having any
other source than the increased elevation.
【答案解析】[词义辨析] normal指人时意为“智力正常的、精神健全的”，合句意。average 意为“平常的、普通的”，与ordinary含义相近。两词相比，average与healthy的含义没有normal与healthy的含义更为接近。另外，average与healthy不是同一丢面上的修饰词，句中逗号起的是一个连词and的作用，故average不能成为答案。如果去掉healthy前面的逗号，那么，答案就可是average了。regular修饰人时意为“(person who)going somewhere and doing something often”，例如：He was one of the regular visitors at the pub where I worked last year. stready也可修饰人，但意为“稳定的、不变的、踏实”。例如：He is a steady young man.