早期的计算机网络从逻辑功能上可分为资源子网与A.信息子网 B.通信子网 C.硬件子网

题型:单项选择题

问题:

早期的计算机网络从逻辑功能上可分为资源子网与

A.信息子网

B.通信子网

C.硬件子网

D.互联子网

考点:计算机等级考试网络技术三级网络技术笔试95
题型:单项选择题

PERTH—Search crews will send a submarine(潜航器)deep into the Indian Ocean on Monday for the first time to try to determine whether signals detected by sound-locating equipment are from the  missing Malaysian plane's black boxes, the Australian head of the search said.

Angus Houst on said the crew on board the Ocean Shield  will send the underwater vehicle sometime Monday evening. The Bluefin 21 submarine can create a sonar(声呐)map of the area to chartany wreckage(残骸)on the seafloor.

The move comes after crews picked up a series of underwater sounds over the past two weeks that were consistent with an aircraft's black boxes.

“We haven’t had a single detection in six days, and l guess it’s time to go under water,” said Houston.

“Analysis of the four signals has reduced the search area on the ocean floor. The experts have therefore determined that the Australian Defense Vessel Ocean Shield will stop searching with the Towed Pinger Locator(拖曳声波定位仪)later today and use the underwater vehicle Bluefin 21 as soon as possible," he said at a news conference in Perth.

But Houston warned the switch to the submarine will not automatically "result in the detection of the aircraft wreckage. It may not.”

He said the submarine will take 24 hours to do each task, including two hours to dive, 16 hours to search the bottom, then two more hours hack up and four hours to download data.

Recovering the plane's flight data and cockpit(飞行员座舱)voice recorders is necessary For investigators to try to figure out what happened to Flight 370, which disappeared on March 8. 

Houston said the search using the submarine will be a slaw and painstaking process.

The submarine takes six times longer to cover the same area as the pinger locator,and will need about six weeks to two months to examine the present underwater zone. The signals are also coming from 4,500 meters (15,000 feet) below the surface, which is the deepest the submarine can dive.

小题1:The submarine will be sent deep into the Indian Ocean on Monday to _____ .

A.create a sonar trap of the area

B.pick up underwater sounds

C.see if the signals detected are from the target black boxes

D.reduce the search area on the ocean floor小题2:According to the passage, the submarine_______ .

A.will download data of the black boxes

B.can find the aircraft wreckage within 24 hours

C.will recover the plane's flight data and voice recorder

D.can dive to a depth of no more than 4,500 meters小题3:The underlined sentences in the passage indicate that______.

A.the switch of the submarine may not function properly

B.the Ocean Shield will switch to submarine when it is necessary

C.the submarine will detect the wreckage of the plane automatically

D.the detection of the wreckage can't be guaranteed by using the submarine小题4:The search will be a slow and painstaking process, mainly because _____ .

A.the underwater sounds were consistent with an aircraft's black boxes

B.the submarine travels slowly and the ocean is deep

C.they haven't had a single detection in six days

D.Ocean Shield stops searching wine the towed pinger locator

题型:单项选择题

膜电位等于K+平衡电位时()

A.Na+通道开放,产生Na+内向电流

B.Na+通道开放,产生Na+外向电流

C.Na+通道开放也不产生Na+电流

D.K+通道开放时不产生K+电流

E.膜两侧K+浓度梯度为零

题型:单项选择题

下列关于正常成人脑脊液细胞计数和分类,叙述正确的是

A.无红细胞,白细胞(0~10)×106/L,主要是淋巴细胞和中性粒细胞
B.红细胞(0~5)×106/L,白细胞(0~10)×106/L,主要是单核细胞和中性粒细胞
C.无红细胞,白细胞(0~10)×106/L,主要是单核细胞和中性粒细胞
D.红细胞(0~5)×106/L,白细胞(0~10)×106/L,主要是单核细胞和淋巴细胞
E.无红细胞,白细胞(0~10)×106/L,主要是淋巴细胞和单核细胞

题型:单项选择题

以下哪一项是脾脏血管瘤的主要表现 ( )

A.类圆形的低回声

B.脾实质内三角形低回声

C.外周减低的混合回声

D.边界清锐的强回声

E.CDFI示有丰富的动脉血流

题型:单项选择题

Of all the employed workers in the United States, 12.5 million are part of a temporary workforce. The United States Bureau of Labor Statistics counts 9.2 percent of workers as those who have______(1) they term "alternative employment arrangements." The government predicts that temporary staffing agencies______(2) experience growth of 49 percent by 2010. If numbers increase at the rate ______ (3), these companies will add 1.9 million new jobs by 2010. That’’s more than any______(4) industry.Temporary workers were the first ones to be affected by the recent economic recession, but they are______(5) to be the first to regain positions as the economy picks up and companies work to rebuild. Employers use temporary workers as a resource because_______(6) offer flexibility and come at a low cost. Many temporaries are categorized as "independent contractors" instead of employees,______(7) allows the employer to avoid______(8) certain taxes. Because they are not required to offer benefits to temporary workers, companies can save a great deal of money by hiring temps. Usually, temporary workers can qualify_______(9) benefits if they work for a staffing company for a certain length of time. Most temps, however, do not continue with one company long______(10) to qualify for them because they regard the position as a step on the ladder to a______(11) position later.According to Richard Wahlquist, president of the American Staffing Association, 75_______(12) of temporary workers hope for transition out of the temporary staffing category______(13) a period of time. Wahlquist finds that temporary workers spend about 11 weeks on various assignments before their______(14) out of the temporary workforce. Many use temporary positions to gain experience and skills______(15) they move on to better jobs. Wahlquist says that the temp workforce as a whole turns______(16) 400 percent each year.Tom Dilworth, research director at the Employment Policies Institute, explains______(17) some workers like having temporary jobs______(18) it affords them a great deal of elasticity with time and everything. Some temps only have a limited______(19) of time to work and temp agencies can help coordinate jobs to fit their schedules. Other sometimes-employees use temporary jobs to get an______(20) to a company from the inside, to get a foot in the door of a certain business or career._______(21) others take temporary positions in hopes their employers will change them over to permanent positions eventually.Nearly all the industries in the United States use temporary workers.______(22) to Tim Costello, coordinator of the North American Alliance for Fair Employment, the growth of temporary labor threatens______(23) job security of permanent workers who fear replacement, as well as the temps who are more accustomed to turnover. He predicts that there will continue to______(24) a gradual shift from permanent employees to contingent staffing, and that such a_____(25) in workplace demographics will "lead to lower wages, poorer working conditions, and more instability."

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