The essential ideas of this method are very simple and can be described briefly as follows: Given a region whose area is to be determined, we inscribe in it a polygonal region which approximates the given region and whose area we can easily compute. Then we choose another polygonal region which gives a better approximation, and we continue the process, taking polygons with more and more sides in an attempt to exhaust the given region.

Fight Against Obesity

    Modem physicists still look mostly at things we can’t see. Either very small things in quantum physics or very big things like galaxies. Putting them together is the main problem of modem physics. The universe of space and time described by Einstein is made up of the noisy fast-moving little sub-atomic particles and other small things. If you want to know how the universe began - with a tiny size but very big mass, then you need a theory that fits both together. At the moment, the theory suggests that the things we can see—stars and planets etc. make up only 5% of the universe. The rest is 25% “dark matter” and 70% “dark energy”. A theory that could explain all that would be a “theory of everything”—the real laws of nature. There arc already suggestions of what it might be. Scientists think that the laws of nature might be rather simple, even though the real world is full of strange and beautifully complicated things. One suggestion is called “string theory”，the idea is that inside every particle there is some energy that is like the string of a musical instrument—the way it vibrates makes a different sort of particle. At the moment they say there are eighteen sorts.

Which of the following is NOT mentioned by Pete McGrail, according to the passage?

All the following words in the passage refer to the same thing EXCEPT_______.

(B)

   What if there was an easy way to take the carbon dioxide from coal power smokestacks and turn it back into a rock that would sit quietly, deep below the earth’s surface? That would get around a key sticking point of current carbon storage schemes, which entail injecting CO2 into porous sedimentary rock formations such as sandstone一that the gas could eventually escape, seeping back up to the surface and into the atmosphere, heating the planet.

     Basaltic rock, which makes up part of the earth’s crust, could be an alternative to sedimentary structures. Minerals within basalt, including magnesium, calcium and iron, gradually react with CO2 to form carbonate crystals inside the pores and scams of basalt, entombing the carbon as a permanent solid. This process, known as enhanced weathering, could capture massive amounts of CO2. Engineers are now trying to turn this bit of chemistry into practice.

     This summer near Wallula, Wash., engineers injected almost 1,000 metric tons of CO2 into layered basalt more than 800 meters belowground. For the next year they are monitoring how quickly and extensively those carbonate crystals appear. Some scientists have presumed that the process takes millennia to occur naturally, but laboratory results suggest it can occur in less than a decade. “It’s not 1,000 years—it’s not even several centuries,” says Pete McGrail, an environmental engineer at Pacific Northwest National Laboratory, which oversees the project. “We’re talking a few years to a few decades to complete the mineralization.” That is quick enough to make a difference in the fight against global warming. Researchers expect to know more in December, when they have their first drill samples.

      Engineers at a second project in Iceland, known as CarbFix, are injecting 1,500 tons of CO2 over two years. They plan to pull samples in May and June 2014 and will continue monitoring through next December, according to Juerg Matter, a researcher at Columbia University who is involved with the work.

      Some scientists are skeptical about whether the carbonate minerals are as leak-proof as hoped. Susan Hovorka, a geologist and carbon-sequestration expert at the University of Texas at Austin, says in certain conditions water deep below the surface could flow across the carbonate crystals and dissolve out the CO2 allowing the gas to possibly seep to the surface. Testing will be needed, she notes, to determine how well basalt will retain the carbon.

      The primary obstacle to carbon storage is policy rather than technical know-how, McGrail says. Without some economic incentive to sequester CO2 in this (or any) fashion, the practice is unlikely to spread. Still, if the pilot projects offer proof that the gas can be locked underground and policy makers follow with a tax on carbon, basalts could provide a viable storage option. About a quarter of India’s many coal-fired power plants sit atop a huge basaltic formation known as the Deccan Traps. If basalt can put our global warming villain back from whence it came, there’s a whole lot of CO2 ready to lock.

What does the passage mainly discuss?

What can be said about the present carbon storage schemes, according to the passage?

The term “enhanced weathering” in line 4, para. 2 most probably refers to______.

The word “behemoth”in line 2, para. 3 refers to_______.

What can be inferred from the passage about the quantum computer?

(A)

  The record-smashing quantum computer reminds me of Prince of Persia. A dizzying and prisms that stretch across the room, it looks rather like the light-directing puzzles common in such video games. I long to twist the lenses and shoot laser beams everywhere.

   That wouldn’t make me popular here. A quiet stillness pervades the Centre for Nanoscience and Quantum Information, part of the University of Bristol. Because quantum states are fragile, the building’s design dampens vibrations and even filters the power supply to remove electrical noise. Each part of the machine spread before me is carefully aligned so that mixing a pair of light beams carries out a specific calculation. Now, it’s set to tum 21 into 3 and 7, the two prime numbers that it is divisible by. It is the biggest number a quantum computer has ever broken into primes using the famous quantum protocol, Shor’s algorithm. Still, I can do the same thing in my head—so what’s the big deal?

    The answer is clearer at my next stop, where I see a wafer of 20 or so chips, each a few centimeters long and made of silicon dioxide. Although not yet as capable as the behemoth I first encountered, these chips are the next stage in the lab’s attempt to build quantum computers that outperform even the best non-quantum machines.

     Information on an ordinary computer is stored as bits, which can be either a 1 or a 0. Quantum bits, or qubits, are both at once, so a large array could process a great deal more information. But assembling even a handful of qubits is tough because of their fragility, so the best way to scale up is to scale down. “You could potentially start doing bigger and more complicated experiments,” says my guide, physicist Graham Marshall. “But can you make it so that it doesn’t feel the presence of the moon, or the movement of tectonic plates? There is a limit to how well you can stabilize something on that scale.”

     That’s where the chips come in. Instead of using glass prisms to mix photons, channels filled with silicon nitride are etched into the chips’ surface in patterns that I can just make out The channels confine and steer photons, guiding them so that they become “entangled”— a quantum properly needed for computation. This should lead to computers that are easier to stabilize and so can scale up.