某电热水壶及铭牌如图所示,装入1.5kg20℃的凉水,通电正常工作6分钟即被烧开

题型:计算题

问题:

某电热水壶及铭牌如图所示,装入1.5kg20℃的凉水,通电正常工作6分钟即被烧开至100℃.已知水的比热容c=4.2×103J/(kg·℃).求:

(1)该过程中水吸收的热量.

(2)电热水壶的效率.

考点:热量的计算能量转化效率电功或电能的计算
题型:计算题

—Where can I buy some books, Simon?

—Go to the _______ in the shopping mall in Old Street. You will find many books there.

A.restaurant

B.bookshop

C.cinema

D.library

题型:计算题

描述特发性门静脉高压症错误的是

A.肝实质呈硬化声像 

B.门静脉管壁增厚管腔狭窄 

C.肝实质回声正常 

D.肝静脉多无异常改变 

E.无肝炎及肝功能异常史

题型:计算题

梓白皮功效与作用

题型:计算题

下列说法不正确的是

A.二氧化硅可用于制光导纤维

B.工艺师利用氢氟酸刻蚀石英制作艺术品

C.金属铝既能溶于酸又能溶于碱

D.从海水中提取溴的过程中,既发生化学变化又发生物理变化

题型:计算题

While some international couriers are showing signs of exhaustion, EMS (Express Mail Service), the generic name for the courier services of post offices, seems to be finding its stride. Known as Datapost in Britain, as Chronopost in France, and as A1-Barid al-Mumtaz in Saudi Arabia, EMS is now second in the international courier business (jointly with TNT Skypack). Last year it delivered 5.6 million items, weighing less than 20 kilograms each, across borders. That and its annual growth rate of around 5 percent have worried DHL, the market leader, enough for it to counter-attack in the Courts.
On October 26, a Dutch judge ruled against DHL on all three counts filed against the Dutch post office: that the three-initial name was too close to DHL’s; that the orange lines in the EMS logo were too similar to DHL’s dark red ones; and that the claim to the widest route system in the world was unfounded. DHL has threatened the Swiss post office with similar action, but it may reconsider after the Dutch ruling.
EMS has some advantages over the private couriers. One is a dense ready-made network of offices, especially in Europe, the avowed target area of the private couriers. Another advantage is a long tradition of working with customs authorities. In a business where minutes count, it pays to have good friends at customs. That advantage particularly irritates the private couriers because there is no legal way to combat such unquantifiable coziness.
The private courier services are also annoyed because in countries like Switzerland and Italy, where the post office is officially a monopoly, they pay it a fee. In Switzerland DHL says it pays more than SFr lm ($ 708,000) "to the competition" each year. In France the couriers have won a battle for exoneration.
Although governments are under little pressure to keep prices artificially low, EMS is often cheaper than the private couriers, but not always. A recent test in Britain (on a domestic route) showed Datapost about halfway between the least and the most expensive, but gave it full marks for speed and service.
Each national EMS is free to set its rates and follow its own rules on things like bulk discounts. The Universal Postal Union, based in Berne, determines how costs and revenues are split between sending and receiving countries, and standardizes procedures. More than 100 postal administrations have linked into the system—and more are coming, including Russia’s. That makes the feisty EMS particularly happy since its rivals have not been allowed to serve anywhere in Russia.

The passage focuses primarily on ______.

A. problems of post offices in Britain
B. the new courier service—EMS
C. the competition between private and international courier services
D. differences between EMS and DHL

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