如图所示为一磁流体发电机示意图,A、B是平行正对的金属板,等离子体(电离的气体,

题型:选择题

问题:

如图所示为一磁流体发电机示意图,A、B是平行正对的金属板,等离子体(电离的气体,由自由电子和阳离子构成,整体呈电中性)从左侧进入,在t时间内有n个自由电子落在B板上,则关于R中的电流大小及方向判断正确的是(  )

A.I= ,从上向下

B.I= ,从上向下

C.I= ,从下向上

D.I= ,从下向上

考点:电流路端电压
题型:选择题
已知在三角形ABC中,AB=2,AC=3,∠BAC=θ,若D为BC的三等分点〔靠近点B一侧).则
AD
BC
的取值范围为______.
题型:选择题

1949~1978年我国在计划经济条件下,居住区按照街坊、小区等模式统一规划、统一建设,其中有代表性的小区有()

A.北京夕照寺小区

B.上海番瓜弄

C.北京方庄居住区

D.北京百万庄居住区

E.广州滨江新村

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男性,80岁,经常饱餐后上中腹痛,仰卧位加重伴慢性腹泻,突起腹部绞’痛,呕吐,腹泻,腹胀伴休克

A."铅管"征
B."鹅卵石"征
C."鸟嘴"征
D."杯口"征
E.充盈缺损

题型: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.

5()

A.over

B.across

C.within

D.above

题型:选择题

衡量电脑图片的清晰程度时一般选用()单位。

A、点/英寸

B、线/英寸

C、像素/厘米

D、像素/英寸

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