题目内容：
阅读材料，回答题。Nanotechnology Many of the grand challenges of today and the future are found in the question: "How are we going to solve the problems and make serious improvements in industrial manufacturing, disease control, environmental pollution control, global climate change, food production, transportation, communication, and others?"
Nanotechnology ( 纳米技术 ) promises to make revolutionary contributions.Within the next few years we can expect to see major improvements. Here are some possibilities the things to come.Nanotechnology is fundamentally changing the way materials and devices will be produced in the future.
Nanostructures, ceramics, polymers, metals, and other materials will have greatly improved mechanical properties.In fact, with the ability to build things atom-by-atom and molecule-by-molecule there will be new classes of structural materials.Nanotechnology will enable products to be lighter, stronger, smarter, cheaper,cleaner, and more precise.
The ability to synthesize nanoscale budding blocks with precisely controlled size and composition and then to assemble them into larger structures with unique properties and functions will revolutionize segments of the materials manufacturing industry. Nanotechnology is expected to bring about lighter, stronger, and programmable materials ; reductions in life-cycle costs through lower failure rates; innovative devices based on new principles and architectures ; and use of molecular cluster manufacturing.
Nanotechnology will provide new tools for medicine.It could radically change the way surgery is done.It will make it possible to do molecular scale surgery to repair and rearrange cells.Since disease is the result of physical disorder, misarranged molecules and cells, medicine at this level should be able to cure most diseases.
Mutations in DNA could be repaired and cancer cells, toxic chemicals, and viruses could be destroyed through use of medical Nan devices.
Nanotechnology enabled increases in computational power will permit the characterization of macromolecular networks in realistic environments.Such simulations will be essential elements in the development of biocompatible implants and in the drug discovery process. Nanotechnology has the potential to significantly impact energy efficiency, storage, and production, Nanotechnology can change the economics of energy production.
The passage deals mainly with__________. A．grand challenge in manufacturing, medicine and computer industry
B．possibilities of nanotechnology's contributions in the future
C．great changes caused by nanotechnology
D．practical application of nanotechnology
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