以下用电器正常工作时的电功率最接近1瓦的是 ( ) A.白炽灯 B.手电筒 C.

题型:选择题

问题:

以下用电器正常工作时的电功率最接近1瓦的是   (    )

A.白炽灯

B.手电筒

C.电冰箱

D.电饭锅

考点:电功率,额定功率
题型:选择题

数码录音笔的连续录音时间一般可以达到( )。

A.40~60min

B.90min

C.3h

D.5~8h

题型:选择题

机械加压送风量应满足走廊至前室至楼梯间的压力呈递增分布,且有前室或封闭避难层(间)与走道之间的压差应为()Pa。

A.25~30

B.35~40

C.45~50

D.55~60

题型:选择题

某大型电力工程公司在海外发现一项新的电力工程项目机会,需要招投标。该项目若中标,则需前期投入200万欧元。考虑距离最终获知竞标结果只有两个月的时间,目前欧元/人民币的汇率波动较大且有可能欧元对人民币升值,此时欧元/人民币即期汇率约为8.38,人民币/欧元的即期汇率约为0.1193。公司决定利用执行价格为0.1190的人民币/欧元看跌期权规避相关风险,该期权权利金为0.0009,合约大小为人民币100万元。据此回答以下问题。

该公司需要人民币/欧元看跌期权手。()

A.买入;17

B.卖出;17

C.买入;16

D.卖出:16

题型:选择题

直流电动机的调速方法有().

A、改变电动机的电枢电压调速

B、改变电动机的励磁电流调速

C、改变电动机的电枢回路串联附加电阻调速

D、改变电动机的电枢电流调速

题型:选择题

Questions 11-15 are based on the following passage.
Davis, California, like many other American cities, has been threatened by unchecked growth, swarming automobiles, and steeply rising energy costs. But unlike towns and cities which leave energy policy to the federal government or energy corporations, the citizens of Davis have acted on their own.
After lengthy debate, Davis’ City Council moved to curb growth. It turned against the automobile and embraced the bicycle as a means of transport. It sponsored an inquiry into energy uses and endorsed a series of measures aimed at reducing energy consumption by as much as one half. It cut back the use of petroleum-derived pesticides on the thousands of trees and shrubs that shade the city’s streets, adopting instead a policy of biological control for insects. The city’s own cars and trucks have been transformed into a fleet of compact vehicles. When a Davis employee has to get around town, he borrows a bike from the city rack. Davis even passed a law formally and solemnly sanctioning the clothesline.
The citizens of Davis have been involved in progressive city planning and energy conservation since 1968, when they persuaded the City Council to facilitate bicycle transportation by developing a system of bikeways. The City’s general plan for development, drawn up in 1972, was based on questionnaires distributed to residents. When a survey of residents showed that automobiles represented 50 percent of energy consumption and space heating and cooling accounted for 25 percent, transportation and building construction became important focal points in the Davis plan.
Armed with survey information revealing that a building’s east-west orientation on the lot, as well as its insulation, window area, roof and wall colors, overhang shading, and other factors greatly influenced space heating and cooling needs, the City Council drew up a building construction code which greatly reduced the cost of winter heating and eliminates the need for air conditioning even on Davis’ hottest (114°) day. To demonstrate to local builders and developers methods for complying with the new code, Davis built two model solar homes, a single-family dwelling which takes advantage of natural southern exposure sunlight and a duplex adaptable to difficult siting situationswhere direct sunlight is blocked.Many of Davis’measures simply facilitate natural solar heating or sun-shading. Where most communities require that fences be built close to houses, Davis realized that practice meant blocking winter sunlight. New fences in Davis must be placed closer to the street, giving residents the benefit of natural solar heat in winter. Reducing required street widths provides more shade and saves asphalt to boot.
Davis’ other energy conserving moves run the gamut—from a city ordinance encouraging cottage industry (to cut down on commuting and the need for new office building construction) to planting evergreens on city streets to reduce leaf pickup in the fall, from a ban on non-solar swimming pool heaters to a recycling center that supports itself by selling $3,000 worth of recyclables a month.

Why did Davis build model solar homes instead of just one

A.To show what they could do when they put their minds to it.

B.To show that even the hottest days could be mastered without air conditioning.

C.To demonstrate that even multiple dwelling in difficult locations could be solar powered.

D.To indicate that other cities were inadequate to the job.

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