问题 单项选择题

下列选项中,关于金属卤化物灯说法错误的是( )。 .

A.发光效率高,光色接近自然光
B.显色性好,即能让人真实地看到被照物体的本色
C.紫外线向外辐射少,但无外壳的金属卤化物灯则紫外线辐射较强,应增加玻璃外罩,或悬挂高度不低于14m
D.平均寿命比高压汞灯要长将近2倍

答案

参考答案:D

解析: 金属卤化物灯的特点如下:
(1)发光效率高,光色接近自然光。
(2)显色性好,即能让人真实地看到被照物体的本色。
(3)紫外线向外辐射少,但无外壳的金属卤化物灯则紫外线辐射较强,应增加玻璃外罩,或悬挂高度不低于14m。
(4)平均寿命比高压汞灯短。
(5)电压变化影响光效和光色的变化,电压突降会自灭,所以电压变化不宜超过额定值的±5%。
金属卤化物灯主要用在要求高照度的场所、繁华街道及要求显色性好的大面积照明的地方。

阅读理解

A severe heatwave sweeping India, with temperatures of almost 44ºC, the highest in 52 years, has killed at least 80 people this month, officials said on Sunday. The hot weather, which officials say would continue over northern, north-western and central India in the next 48 hours, also may have some impact on wheat production, exporters and flour-mill associations said.

  New Delhi recorded a maximum temperature of 43.7ºC on Saturday, indicating a hot summer in the next two months in the nation's capital and other parts of northern and eastern India. The highest temperature in the past 24 hours was 47ºC at Ganganagar city, in Rajasthan state. Summer temperatures have been 4ºC-6ºC above normal over most parts of northern and central India since March, weather officials said.

  In the eastern state of Orissa, authorities have decided to shut down schools from next Tuesday, advancing the annual summer holiday. Authorities said they were investigating reports of 53 deaths from various parts of the state.

  "District collectors have been asked to investigate and submit reports on other deaths," Bhimsen Gochhayat, a government official said. Other deaths were reported from northern state of Uttar Pradesh and central Madhya Pradesh states.

  India is expected to produce about 82 million tons of wheat in 2009-2010, but there could be a shortage of 1-1.5 million tons due to the heatwave, said Veena Sharma, Secretary General of the Roller Flour Millers Federation of India. "Most of the harvesting is over, but there definitely will be a slight shortage of 1-1.5 million tons due to the extreme weather conditions," she told Reuters.

India is relying on an abundant wheat crop to make up for a 14.2% drop in rice output, the major summer-sown food grain, marred by the worst monsoon (季风)in 37 years last year. Weather officials say with summer temperatures in India set to remain above average, there were hopes of heavy rains at the start of the monsoon season that will help early sowing of rice, soybeans and lentils. 

小题1: The purpose of the passage is ____________.

A.to tell a piece of news of a heatwave

B.to record the highest temperature in India

C.to report the deaths in the heatwave

D.to inform people of a drop of rice output小题2: Which of the following is TRUE according to the passage?

A. The highest temperature in the history of India was 44ºC.

B. Schools were closed because of the hot weather throughout India.

C. India is expected to produce about 82 million tons of rice in 2009-2010.

D. India has a good harvest of wheat while the rice output is decreasing.

小题3: The underlined word “marred” in the last paragraph probably means “___________”.

A.reduced

B.damaged

C.blown

D.followed小题4:What is the main idea of the passage?

A.A severe heatwave would continue over India.

B.At least 80% people were killed in the disaster this month.

C.A severe heatwave swept India with a great loss.

D.A slight shortage of 1-1.5 million tons is due to the heatwave.

名词解释