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穷举测试的方法对于所有项目程序都是可行的吗？

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如图所示一台路由器连接3个以太网。
请根据图中给出的参数回答如下问题：
(1)该TCP／IP网络使用的是哪一类IP地址。
(2)写出该网络划分子网后所采用的子网掩码。
(3)系统管理员将计算机D和E按照图中所示结构连入网络并使用所分配的地址对TCP／IP软件进行常规配置后，发现这两台机器上的网络应用程序不能够正常通信。这是为什么？
(4)如果你在主机C上要发送一个IP分组，使得主机D和主机E都会接收它，而子网3和子网4上的主机都不会接收它，那么该IP分组应该填写什么样的目标IP地址？

材料1说明了什么问题？为什么？

The giant panda, the creature that has become a symbol of conservation, is facing extinction. The major reason is loss of habitat, which has continued despite the establishment, since 1963, of 14 panda reserves. Deforestation, mainly carried out by farmers clearing land to make way for fields as they move higher into the mountains, has drastically contracted the mammal's range. The panda has disappeared from much of central and eastern China, and is now restricted to the eastern flank of the Himalayas in Sichuan and Gansu provinces, and the Qinling Mountains in Shanxi province. Fewer than 1,400 of the animals are believed to remain in the wild.
Satellite imagery has shown the seriousness of the situation ; almost half of the panda's habitat has been destroyed or degraded since 1975. Worse, the surviving panda population has also become fragmented; a combination of satellite imagery and ground surveys reveals panda "islands" in patches of forest separated by cleared land. The population of these islands, ranging from fewer than ten to more than 50 pandas, has become isolated because the animals are unwilling to cross open areas. Just putting a road through a panda habitat may be enough to split a population in two.
The minuscule size of the panda populations worries conservationists. The smallest groups have too few animals to be viable, and will inevitably die out. The larger populations may be viable in the short term, but will be susceptible to genetic defects as a result of inbreeding.
In these circumstances, a more traditional threat to pandas--the cycle of flowering and subsequent withering of the bamboo that is their staple food--can become literally species-threatening. The flowerings prompt pandas to move from one area to another, thus preventing inbreeding in what would otherwise be sedentary populations. In panda islands, however, bamboo flowering could prove catastrophic because the pandas are unable to emigrate.
The latest conservation management plan for the panda, prepared by China's Ministry of Forestry and the World Wide Fund for Nature, aims primarily to maintain panda habitats and to ensure that populations are linked wherever possible. The plan will change some existing reserve boundaries, establish 14 new reserves and protect or replant corridors of forest between panda islands. Other measures include: better control of poaching, which remains a problem despite strict laws, as panda skins fetch high prices; reducing the degradation of habitats outside reserves; and reforestation.
The plan is ambitious. Implementation will be expensive--56.6 million yuan(US 12.5 million) will be needed for the development of the panda reserves--and will require participation by individuals ranging from villagers to government officials.
Summary
The survival of the giant panda is being seriously threatened. Panda numbers have already seriously decreased. This is largely because the overall size of their【61】has been reduced, and habitable areas are now disconnected from each other. Two results are that pandas are more prone to【62】problems and are unable to move around freely to follow the growth cycles of the bamboo that they eat. A new plan aims to【63】existing panda habitats and to join many of them together. This plan also includes reforestation and the creation of【64】To succeed, everyone, including both the government and【65】, will have to cooperate.
(61)

Section C
The Dog with the Golden Nose
Jiggs, the chimpanzee that starred in over fifteen Tarzan films in the 1930s, was paid thousands of pounds. The owner of Bart, an Alaskan brown bear, was paid a million dollars for letting Bart appear in the film The Edge. A racehorse called Rock of Gibraltar is worth an estimated ￡ 100 million. Now there is Keela, a dog doing a great job and getting well remunerated for it.
Keela, a 16-month-old springer spaniel, has become such an asset to the South Yorkshire Police that she now earns more than the chief constable.
Her sense of smell, so keen that she can find traces of blood on weapons that have been scrubbed ‘clean’, has her so much in demand by forces up and down the country that she is hired out at ￡ 530 a day, plus expenses.
Thought to be the only one of her kind, this ‘crime scene dog’ earns nearly ￡ 200, 000 a year. Her daily rate, ten times that of ordinary police dogs, pay her more than the chief constable, Meredydd Hughes, who picks up ￡ 129, 963.
Keela’s considerable talent in uncovering minute pieces of evidence that can later be confirmed by forensic tests has put her in the forefront of detective work across Britain. She was drafted in to help after the stabbing of the young mother, Abigail Witchalls, in Surrey, and has been involved in high-profile cases across 17 forces, from Devon and Cornwall to Strathclyde.
PC John Ellis, her handler, said that the police send for Keela when the scenes of crime squads fail to find what they are looking for. ‘She can detect minute quantities of blood that cannot be seen with the human eye,’ he said. ‘She is used at scenes where someone has cleaned up. If blood has seeped into the tiles behind a bath which contained a body, she can find it. '
The spaniel can sniff out blood in clothes’ after they have been washed repeatedly in biological washing powder, and can detect microscopic amounts on weapons that have been scrubbed and washed.
When faced with a ‘clean’ crime scene, Mr Ellis and PC Martin Grimes, Keela’s other handler , will first send in Frankie, a border collie, and Eddie, another Springer spaniel, to pick up any general scent. Then they wheel in the big gun.
‘We take Keela in and she will find the minutest traces of blood,’ Mr Ellis said. ‘It’s not like looking for a needle in a haystack any more. The other two dogs will find the haystack and Keela will find the needle.
While the other dogs bark, Keela has been trained to freeze and pinpoint the area with her nose.
Mr Ellis said Keela’s ‘perfect temperament’ and enthusiasm make her a great asset. ‘We thought we would get one or two deployments a year, but things have just snowballed. Obviously when we are called in by other forces they are charged a fee and it’s quite funny to think she earns more than the chief constable,’ commented Mr Ellis.
Mr Hughes says there are no hard feelings. ‘Keela’s training gives the force an edge when it comes to forensic investigation which we should recognize and use more often.
Mr Ellis and Mr Grimes came up with a special training regime to focus on Keela’s remarkable skills. It has proved so successful that the FBI has inquired about it. ‘The FBI is very interested in how we work because they don’t have this sort of facility in-house and they are looking at setting up their own u-nit,’ Mr Ellis said.
Paul Puffell, of K9 Solutions, a security firm specializing in dog units, said he was amazed at Keela’s abilities. ‘I’ve been working in this business for 25 years and I’ve never heard anything like it,’ he said.
Summary
Keela may not be a(n)【71】like other highly, paid animals, but she is similarly in demand. She has an incredible【72】she can detect blood on clothes, even after they have been washed in washing powder. This makes her especially useful at a (n)【73】. Once her handlers realized she was so exceptional, they invented a special【74】for her. She now makes more money than the【75】__of the police force!
(41)