问题
选择题
若x-2y=-3，则代数式5-x+2y的值是
A．8
B．5
C．2
D．0
答案
答案：A
对所求代数式5-x+2y的后两项提取-1，再把x-2y的值代入计算即可．
解：∵x-2y=-3，
∴5-x+2y=5-（x-2y）=5-（-3）=8．
故选A．
本题考查了代数式求值，解题的关键是注意整体代入．
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若x-2y=-3，则代数式5-x+2y的值是
A．8
B．5
C．2
D．0
答案：A
对所求代数式5-x+2y的后两项提取-1，再把x-2y的值代入计算即可．
解：∵x-2y=-3，
∴5-x+2y=5-（x-2y）=5-（-3）=8．
故选A．
本题考查了代数式求值，解题的关键是注意整体代入．
Passage Three
| Health-care services will account for almost one-fifth of all job growth during the 1996～2005 period. Home health-care aids will assist the elderly, disabled, and seriously ill in the patient’s home instead of a health facility. A large number of openings for this field is expected due to very rapid growth and high turnover. In fact, home health-care aids are expected to more than double in number by the end of 2005. Part of the reason for this increase is the growing population of elderly people. The number of people in their 70s and older is projected to rise substantially. This age group is characterized by mounting health problems that require assistance. There will also be an increasing reliance on home care for patients of all ages. This trend reflects several developments: Efforts to contain (抑制，控制) costs by moving patients out of hospitals and nursing facilities as quickly as possible; the realization that treatment can be more effective in familiar surroundings; and the development of portable medical equipment for in-home treatment. Turnover in this field is high, which is a reflection of the relatively low skill requirements, low pay, and high emotional demands of the work. Therefore, people who are interested in this work and properly suited for it should have excellent job opportunities, particularly those with previous experience. Physical therapy, too, is predicted to increase rapidly through 2005. A growing population of elderly people, who are vulnerable to chronic and debilitating (虚弱的) conditions, means that more therapeutic services will be needed. More young people will also need physical therapy as medical advances save the lives of a larger proportion of newborns with severe birth defects. Growth will also result from advances in medical technology that permit the treatment of more disabling conditions. In the past, for example, the development of hip and knee replacements for those with arthritis gave rise to employment for physical therapists to improve flexibility and strengthen weak muscles. The growing interest in health promotion should also increase the demand for physical therapy services. More employers are now evaluating work sites, developing exercise programs, and teaching safe work habits to employees in the hope of reducing injuries. A shortage of physical therapists that once existed has all but disappeared. The number of physical-therapy education programs has increased, and more graduates have moved into the labor force. Most graduates receive multiple job offers, and job prospects are expected to continue to be excellent. Physical therapists who are willing to work in rural areas will experience even better opportunities. |
The high turnover in the field of home health care reflects ______ .
A．the relatively high skill requirement
B．the high pay of the work
C．high emotional demand of the work
D．bad job opportunities in the field