搜题请搜索小程序“爱下问搜题”
问题 填空题

伏安法测电阻时，我们采取的探究方法是______，所要测出的物理量是______和______；其中滑动变阻器主要作用是______．

答案

（1）伏安法测电阻的原理是：欧姆定律，即：R=

U
I
，则需要测量的物理量是导体两端的电压和通过导体的电流．

所以伏安法测电阻时，我们是利用电压表和电流表通过实验测量，采取的探究方法是实验法；

（2）滑动变阻器主要作用是：

①连接电路时，电阻如果短路，滑动变阻器起保护电路的作用．

②滑动变阻器能改变定值电阻两端的电压和电流，能完成多次实验，求电阻的平均值，减小误差．

故答案为：实验法；导体两端的电压；通过导体的电流；保护电路；改变电阻两端的电压进行多次测量求平均值，减小实验误差．

单项选择题

患者，男，68岁。诊为肺癌，症见唇甲紫暗，咳痰不爽，胸痛气急，舌有瘀点，脉弦。其证型是（）.

A.脾肺气虚

B.痰热搏结

C.气滞血瘀

D.痰湿内阻

E.肺气郁闭
查看答案
单项选择题

In the United States, older people rarely live with their adult children. But in many other cultures children are expected to care (1) their aged parents. In some parts of Italy, the percentage of adult children who (2) with their parents (3) 65 to 70 percent. In Thailand, too, children are expected to take care of their elderly parents; few Thai elderly live (4) . What explains these differences in living arrangements (5) cultures Modernization theory (6) the extended family household to low levels of economic development. In traditional societies, the elderly live with their children in large extended family units for economic reasons. But with modernization, children move to urban areas, leaving old people (7) in (8) rural areas. Yet modernization theory cannot explain why extended family households were never common in the United States or England, or why families in Italy, which is fully modernized, (9) a p tradition of intergenerational living. Clearly, economic development alone cannot explain (10) living arrangements. Another theory associated intergenerational living arrangements with inheritance patterns. In some cultures, the stem family pattern of inheritance (11) . (12) this system, parents live with a married child, usually the oldest son, who then (13) their property when they die. The stem family system was once common in Japan, but changes in inheritance laws, (14) broader social changes brought (15) by industrialization and urbanization, have (16) the (17) .In 1960 about 80 percent of Japanese over 65 lived with their children; by 1990 only 60 percent did-a figure that is still high (18) U.S. standards, but which has been (19) steadily. In Korea, too, traditional living arrangements are (20) : the percentage of aged Koreans who live with a son declined from 77 percent in 1984 to 50 percent just 10 years later. Although most elderly Koreans still expect to live with a son, their adult children do not expect to live with their children when they grow old.

17（）

A.authority

B.usage

C.habit

D.tradition
查看答案