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Sending a robot into space to gather information is a viable option, but should only be regarded as that--an option. Even the most technologically advanced robots cannot and should not replace manned missions to outer space. Certainly it is cheaper and less dangerous to launch a computer probe that can gather reams of data, but often the information obtained by a machine only serves to produce more questions than it answers. Therefore, the space program should allow manned missions to follow up on those initial information-gathering robotic ventures.While manned missions are more costly than are unmanned missions, they are also more successful. Robots and astronauts use much of the same equipment in space, but a human is more capable of calibrating those instruments correctly and placing them in appropriate and useful positions. A computer is often neither as sensitive nor as accurate as a human in managing the same terrain or environmental circumstances. Robots are also not as equipped as humans to solve problems as they arise, and robots often collect data that is not helpful or even desired. A human, on the other hand, can make instant decisions about what to explore further and what to ignore. Select the sentence that offers potential advantages to using robots as information gatherers in space.（）
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Over the years there have been countless fans of the classic Hanna-Barbera cartoon character Yogi Bear. The cartoon series enjoyed by young and old alike revolved mostly around the misadventures of this loveable bear and his sidekick Boo-Boo as they attempted to snag "pic-a-nic" baskets in the made-up land of Jellystone Park. It’s not often that people think about where the ideas for these cartoons characters came from, which brings up an interesting point: do bears actually search for food left in picnic baskets and unattended campsites Anyone who has watched an episode of the classic cartoon can see that the bears’ behavior goes far beyond the limits of what is natural. The thing that must be explored, then, is which of those humorous antics were license on the part of Hanna-Barbera, and which were actually based on a bear’s normal behaviors.
You know that x is a positive integer. Which of the following statements individually provide(s) sufficient additional information to determine whether the square root of x is also an integer Select all such statements.（）
The coming of the railways in the 1830s transformed society and economic life by providing, for first time, mass transport for passengers and goods. One man, George Stephenson, is sometimes called the "father of the railways" although he did not invent either the locomotive or the rails. The basic idea of a "railway" was an old one, mainly used in mines, in the sixteenth century, miners found it was easier to push their loads in a truck with wooden wheels over planks than to push it through mud and over rocks. Later they developed plateways, which were long pieces of iron fixed to the ground to channel the wheels along, in place of the wooden planks. So these were the early rails, but what about the locomotives Locomotive is short for locomotive engine, which means a self-propeled engine. Steam engines were well--known in mines and factories by the early nineteenth century, and some people had the idea of putting them on wheels as a substitute for human and horse power in pulling loads. The first such locomotive was built by an English man called Richard Trevithick in the year 1804. His engine worked but there were serious technical problems. The locomotives were very heavy, for example and kept breaking the track. At this stage, they didn’t even offer any economic advantage. So locomotives didn’t really catch on then. One early enthusiast, though, was George Stephenson, who had been doing various mechanical and engineering jobs at coal mines since he was a boy. He didn’t have much formal education, but he was good at fixing things, from shoes to clocks to steam engines. He had devised on ingenious safety lamp for the mines, one that wouldn’t cause explosions underground. The engines at the mines were mostly stationary fixed machines for pumping water or for winding or hauling loads by cables. But George Stephenson also built a number of experimental locomotives. That’s how he came to be involved, in september 1825, with the opening of an innovative railway line in northern England. Until then, the only railways had been small, private lines carrying coal or metal ores from mines to the nearest river or canal. The Stockton and Darlington railway was different. It was a public railway and for this new railway, George Stephenson desired a locomotive called "locomotion" which was used to haul passengers from the first day. The idea of carrying passengers as well as freight was born and soon turned out, quite unexpectedly, to be a phenomenal success. The booming Industrial Revolution also meant a growing demand for goods trans- port, which the railways were able to meet. But although railways were now becoming established, locomotives weren’t. They still faced competition from both horsepower and stationary winding engines. This is really where George Stephenson crones in. The next big railway project was a fifty - kilometre line to link Liverpool and Manchester, again in northern England. The directions couldn’t decide which method of haulage they should go for: On the whole they favoured winding engines, stationed every two or three kilometres along the track. But Stephenson, who was on the board of directors, argued doggedly in favor of locomotives, and in the end they agreed to offer a prize to see if anyone could build one good enough to do the job. Stephenson entered the contest, of course—he was competitive by nature anyway — with locomotive built by his son, Robert George him- self was too busy surveying the railway line but Robert was also an excellent engineer and he designed a magnificent engine called the Rocket, the true ancestor of the modern steam locomotive. The most important feature of the Rocket was its multi - tube boiler, instead of just one wide tube carrying hot air from the furnace through the water of the boiler, heating it into steam, the Rocket had twenty five little tubes, which gave it a much greater surface area in contact with the water, so it made more steam, much faster. It also had a blast pipe. In other words, exhaust steam was sent up the chimney in a rapid blast which pulled a draught of air across the furnace, making it burn better. All this made the locomotive more powerful. On the last van of the trials, George opened the throttle up and the Rocket achieved an amazing speed of thirty miles an hour. This really proved the feasibility of using locomotives to haul trains on rail-ways. In a true sense, plateways are the earliest and most primitive railways invented by ______.
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