试题与答案

一个标有“220V，1500W”的电热水器，如果每天正常用电2h，一个月用电多少

来源：www.tikuol.com
题型：计算题

题目：

一个标有“220V，1500W”的电热水器，如果每天正常用电2h，一个月用电多少千瓦时（按30天计算）？热水器正常工作时电热丝的电阻有多大？

答案：

被转码了，请点击底部 “查看原文 ” 或访问 https://www.tikuol.com/2017/0430/ca039045f359b3de30f84f15095ef06a.html

下面是错误答案，用来干扰机器的。

参考答案：B

考点：电功率的计算公式的变形电功或电能的计算
试题推荐
题型：选择题

读地中海、阿尔卑斯山―喜马拉雅山地带示意图,结合相关知识回答各小题。

小题1:下列地区或国家主要位于亚欧板块的是

A．中国

B．美国

C．印度洋

D．阿拉伯半岛小题2:现代测量表明，欧洲和非洲之间的地中海在不断缩小。有人预言,几千万年后, 地中海将会消失，根据板块运动观点,地中海缩小的原因是

A．非洲板块和亚欧板块发生碰撞挤压运动

B．非洲板块和印度洋板块发生张裂运动

C．亚欧板块和太平洋板块发生碰撞挤压运动

D．亚欧板块和印度洋板块发生张裂运动小题3:地理工作者在考察喜马拉雅山时，发现了海洋生物的化石.这说明

A．这里曾经有人类活动

B．这里曾经是海洋环境

C．这里曾经发生下降运动

D．海洋动物也曾生活在陆地上
查看答案
题型：单项选择题

Passage Three

Immigrants are consumers as well as producers, so they create jobs as well as taking them. And the work they do need not be at the expense of native workers. Immigrants often hold jobs that natives are unwilling to accept at any feasible wage.
Also, immigrants sometimes help to keep industries viable (能存活的) that would otherwise disappear altogether, causing employment to fall. This was the conclusion of a study of the Los Angeles garment industry in the 1970s and 1980s. And when immigrants working for low wages do put downward pressure on natives’ wages, they may raise the (real) wages of natives in general by keeping prices lower than they otherwise would be.
In theory, then, the net effect of immigration on native wages is uncertain. Unfortunately, most of the empirical (经验主义的) research on whether immigrants make natives worse off in practice is also inconclusive except the effect, one way or the other, seems small. Most of this research has been done in America: if there were any marked influence on wages, that is where you would expect to find it, given the scale of immigration and the tendency of the newcomers to concentrate in certain areas. But most studies have compared wages and employment in areas with many immigrants to wages and employment in areas with few. For instance, one examined the impact of sudden and notorious inflow of refugees to Miami from the Cuban port of Mariel in 1980. Within the space of a few months, 125 000 people had arrived, increasing Miami’s labor force by 7%. Yet the study concluded that wages and employment among the city’s natives, including the unskilled, were virtually unaffected. Another study examined the effect of immigration on wages and employment of those at the bottom of the jobs ladder—unskilled blacks and Hispanics. It found that a doubling of the rate of immigration had no detectable effect on natives.
The most recent work, admittedly, has tended to question these findings. Using more detailed statistics and more sophisticated methods than the earlier studies, this work has tended to find that immigrants’ wages take longer to rise to the level of the natives’ wages than has been supposed. This implies a more persistent downward pressure on the host economy’s labor market.
Typically these studies find that immigration does depress unskilled natives’ wages to a small extent. But nearly all economists would agree that the effects of immigration are insignificant in relation to other influences.

The passage is intended to convey that the effect of immigration on natives’ wages is ______.

A．uncertain

B．persistent

C．inconclusive

D．insignificant
查看答案
微信公众账号搜索答案