若要定义日期/时间变量,需用( )标识。A.Integer B.Long C.Si

题型:单项选择题

问题:

若要定义日期/时间变量,需用( )标识。

A.Integer

B.Long

C.Single

D.Date

考点:计算机等级考试ACCESS二级ACCESS笔试
题型:单项选择题
方程组
2x+ky=4
x-2y=0
的解为正数,则k的取值范围是(  )
A.k>4B.k≥4C.k>0D.k>-4
题型:单项选择题

在测定空气里氧气含量的实验中:在集气瓶内加入少量的水,并做上标记,余  下的容积五等分.用弹簧夹夹住乳胶管.点燃红磷伸入瓶中并塞上瓶塞.待红磷熄灭并冷却后,打开弹簧夹,观察广口瓶内水面变化情况.实验完毕甲、乙、丙同学观察到不同的现象.

甲同学:广口瓶内水面上升,明显小于瓶内空气的

1
5

乙同学:广口瓶内水面上升,明显大于瓶内空气的

1
5

丙同学:广口瓶内水面上升,约等于瓶内空气的

1
5

(1)写出红磷在空气中燃烧的表达式(用化学方程式表示):______.

(2)甲、乙同学针对各自的现象,共作出了下列解释:

①可能使用的红磷的量不足,瓶内氧气没有消耗完全;

②可能未塞紧瓶塞,红磷熄灭冷却时外界空气进入瓶内;

③可能没有夹紧弹簧夹,红磷燃烧时瓶内部分空气受热从导管逸出;

④可能插入燃烧匙太慢,塞紧瓶塞之前,瓶内的空气受热逸出.

上述四种解释,其中属于甲同学的原因是(填序号)______;属于乙同学的原因是(填序号)______;

(3)丙同学实验结束后,广口瓶内含量最多的气体是______,通过本实验,说明该气体具有的物理性质是(填一点)______;具有的化学性质是(填一点)______.

题型:单项选择题

下列原子有三个未成对电子的是(  )

A.N

B.O

C.Cl

D.Mg

题型:单项选择题

大型汽轮发电机定子绕组端部的紧固很重要,因为当绕组端部受力时,最容易损坏的部件是( )。

A.出槽口处

B.焊接接头部分

C.线圈换位部分

D.直槽部分

题型: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.

(18)是()

A.by

B.on

C.with

D.in

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