实验探究：给你一个定值电阻R，请你测量出它的电阻。

[制定计划与设计实验]

（1）根据__________，要测出电阻R需测出________和_______ 。

（2）请你在虚框内设计出实验电路图和完成下图实物图的连接。并测量三次在不同电压下，通过电阻的电流I，求出电阻R。

     

 [进行实验与搜集证据]

实验步骤：（略）

通过实验，得到如下证据：

[交流与合作]

请你讨论下列问题，以便同学交流：

（3）完成上面的实验表格的填写。

（4）写出计算后的电阻R的平均值？（要求有实验过程）

（5）为什么电压增大时，电阻增大？

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.

（12）是（）

A.at

B.under

C.by

D.over