Nearly 5000 farmers are exporting organically-grown produce to Europe afer_________.

A . exposure limits B . concentration limits C . threshold limit values D . substance limit value

A . Each router has an identical link state database. B . External routes are imported into a separate link state database. C . Syn chronization of link state databases is maintained via floodingo f LSAs. D . Information in the link state database is used to build a routing table by calculating a shortest-path tree. E . By default,link state databases are refreshede very 10 minutes in the absence of topology changes.

A .  port security B .  fabric binding C .  IVR D .  port tracking E .  FICON

A .  The bring up protocol automatically detects and overrides any misconfiguration. B .  You can manually configure channel groups， or they can be automatically created. C .  Changes in configuration to the SAN port channel interface must also be made to all members of the channel group. D .  The port channel protocol uses the exchange fabric parameters command to communicate across peer ports in an ISL. E .  The port channel protocol ensures that a set of ports is eligible to be part of the same SAN port channel.

A . crossing situation B . head-on situation C . restricted visibility D . overtaking situatio

A . cross B . crossing C . crossed D . crosse

A . head-on situation B . crossing situation C . overtaking situation D . close-quarters situatio

A.in conjunction with B.apart from C.as such D.on the threshold

To many web-building spiders, most of 【C1】______ are nearly blind, the web is their essential window 【C2】______ the world: their means of communicating, 【C3】______ prey, meeting mates and protecting themselves. A web-building spider 【C4】______ its web is like a man marooned on an island of solid rock, totally out of touch and destined to starve to death. So 【C5】______ is the web to an orb-web spider's survival that the animal will continue to construct new webs daily 【C6】______ it is being starved. For 16 days the 【C7】______ spider builds completely normal webs. Then, as the animal gets scrawnier, it constructs a wider-meshed web using 【C8】______ strands. Such webs would only trap larger prey, which is more 【C9】______ from the perspective of a starving spider. The spider 【C10】______ energy by recycling web protein. It simply eats its own web each evening and reuses it to manufacture 【C11】______ silk. In studies with radioactively labeled materials, it 【C12】______ that 95 percent of web protein reappeared in 【C13】______ web. Most of the energy needed for web-building is used in walking over the strands as they are laid down. Scientists are 【C14】______ by the adaptability of the spider's highly preprogrammed brain, which is larger 【C15】______ its size than the brain of any other invertebrate. If web-building is interrupted, or if some of the 【C16】______ strands are destroyed, the spider 【C17】______ retraces its steps to see where the web is 【C18】______ and then finishes building a 【C19】______ web. One spider will even finish building the incomplete web of 【C20】______ . 【C1】 A．them B．whom C．that D．which

The summer holidays are the best time of the year in England for ___21___ children. The weather is usually so good that they can spend most of their time playing in the garden, or playing in the forests and fields if they live in the ___22___. If they live in big towns, they can usually go to parks to play. In England, not only can the rich people take their children to the seaside. If a factory worker or a bus driver, a street cleaner or a farmer ___23___ to take his wife and children there, he can usually does this like them. Why do people like so much at the seaside？ It's the sea, the sand and the sun. Of course, there are a lot of new things to see, nice thing to eat and exciting things to do. And there are also the feeling of sand under one's feet, of sea water to one's skin, and the warm sun on one's back. Everybody can enjoy himself at the seaside. But when ___24___ comes, the summer holidays are over. Boys and girls ___25___ have a new school year. They will come back to their school again. 21)、 A.countries B.September C.will D.wants E.most 22)、 A.countries B.September C.will D.wants E.most 23)、 A.countries B.September C.will D.wants E.most 24)、 A.countries B.September C.will D.wants E.most 25)、 A.countries B.September C.will D.wants E.most

A white buoy with an open-faced orange diamond on it indicates (). A.danger B.vessels are excluded from the area C.the buoy is a mooring buoy D.operating restrictions are in effect

Researchers have learned that the slapping noise pigeons make when they suddenly take off is the sound of super charged lift. They call it the "clap fling" effect. Here at SRI International scientists try to duplicate the pigeons' thrust. A flashing strobe reveals the secret. Scott Stanford, a scientist at SRI, says, You re looking at the clap fling effect, where the two wings will come together and peel apart 【C2】______ each other, thus augmenting lift 【C3】______ drawing air from the top to the bottom. " This mechanical bug won't get off the ground. 【C4】______ its flapping wings demonstrate a potential propulsion system for robotic birds: man-made rubbery muscle. Roy Kornbluh works at SRI. "There, I'm turning the voltage on and off, and you can see when the voltage is on, the material is larger 【C5】______ when the voltage is off." Super computers show high-speed airflows over supersonic aircraft. But scientists have only begun to see how air flows 【C6】______ really low speeds. Professor Max Platzer of the Naval Postgraduate School, says, "The flapping wing is generating a thrust, this way, this is the basic physics of the phenomenon." It's pelicans--not pigeons--the Navy is looking at. The Navy is looking at the smooth easy flight of pelicans low over water--called "ground effect." Researchers at the Naval Postgraduate School are trying to imitate the pelican's efficiency. Assistant Professor Kevin Jones of the Naval Postgraduate School says, " 【C7】______ flapping the wings, symmetrically, we're 【C8】______ effect imitating ground effect. We now have the same feature a bird sees when it's flying, over a ground plane." An electric motor drives the flapping wings. Researchers here are working 【C9】______ ways to beam power to the tiny bird. David Jenn of the Naval Postgraduate School says, "There's no battery inside of here, so we're going to set this inside the radar beam, and the energy is extracted from the radar beam and will be used to propel the motor." Scientists are learning it's one thing to build an airplane, 【C10】______ quite another to build a bird. 【C1】______

A．Though,but B．But,though C．Though,/ D．But,/

A．bubble B．dwindle C．sway D．shiver

是 否

The summer holidays are the best part of the year for most children.The weather is usually good, so that one can spend most of one’s time playing in the garden or, if one lives in the country, out in the woods and fields.Even if one lives in a big town, one can usually go to a park to play. The best place for a summer holiday, however, is the seaside.Some children are lucky enough to live near the sea, but for the others who do not, a week or two at one of the big seaside towns is something which they will talk about for the whole of the following year. In England, it is not only the rich who can take their children to the seaside; if a factory worker or a bus driver, a street cleaner or a waiter wants to take his wife and children to Southend or Margate, Blackpool or Clacton, he is usually quite able to do so. Now, what is it that children like so much about the seaside？ I think it is the sand, sea and sun more than any other things.Of course, there are lots of new things to see, nice things to eat, and exciting things to do, but it is the feeling of sand under one’s feet, of salt water on one’s skin, and of the warm sun on one’s back that makes the seaside what it is. 1.Summer holidays start _________. A.with July B.as soon as the examinations are over C.in mid-June D.in August 2.After the examination, all pupils leave for home ________. A.by train only B.by air C.by bike D.by either train or car 3.The summer holiday lasts _______. A.as long as two months B.more that two months C.one and a half months D.a little less than two months 4.July and August are the brightest months for most children, for they can _______. A.stay with their parents for all the vacation B.do more reading C.play out of doors D.meet their old friends 5.Children like the seaside so much because they can _______. A.swim in the sea B.play with the sand C.take a sun bath D.do all of the above

A．toofewhogswillberaiseD B．thepricewillbelessthanthemarginalsocialcost． C．thepricewillbelessthanthemarginalsocialbenefit． D．thepricewillbelessthanthemarginalcosttohogfarmers．

A．donation B．supplement C．barn D．surplus

A、f is a surjective homomorphism from V1 to V2 B、f is an injective homomorphism from V1 to V2 C、f is an isomorphism from V1 to V2 D、None of the above