阅读理解。 Though 'nanometer' (纳米) is now a fashionable term all over the world, few people know exactly what it is. It has become a new favorite of producers and sellers in recent years. Many 'high-tech' products bearing the name 'nano' have entered the market, bringing more mysterious feeling to surprised consumers. Nanometer is a very small length unit of measure, and is very small. One millimeter is 1000 micrometers, and one micrometer is 1 000 nanometers. That is, one nanometer is one billionth of a meter. Nano materials are solid materials made up of particles (粒子) or crystallites (晶体) of less than 100 nanometers in size. Then, is a cup made of nano material really any different from an ordinary cup in function as far as how it works? Are nano cups really so wonderful? A reporter went to the Institute of Nanomedicine, which is the first such institute of such a sort in the world and the only one in China, specializing in researching the investigation of the application of nano technology into medicine. A water molecule (分子) is made up of 2 hydrogen atoms and l oxygen atom. It can be changed only by a special way of controlling of the atoms. The material made into the cup can have nanometer particles. But it cannot change the chemical and physical properties of the water contained in the cup. The water in it is still water. When people drink it, it will produce no special effect on human body. Professor Ji who worked in the Institute of Nanomedicine told the reporter, so far, the investigation of nano materials is still limited in the laboratory. No commercial micro products can be produced yet. With the present level of science and technology, the time of everyday goods made of nanometer materials is still years away. The products labeled with nano marks in the market now are only traditional products coated with a thin layer of nanometer material, which makes them more abrasion resistant (耐磨), much easier to be cleaned, or oil resisting or moth proof (防蛀). Professor Ji explained that nano cup is a real cup. It can also be included in the list of nano products in a certain sense. But the nano cup has not changed its property and function as a cup. It is not a magical medicine for curing and health care. 1. Which of the following shows the right relationship? [     ] A. nanometer B. micrometer C. nanometer D. millimeter 2. It can be inferred from the passage that _____. [     ] A. nano materials have been put into use in daily goods B. real nano products haven't become available for people C. the nano cup is very effective in curing and health care D. real nano products are being produced by some companies 3. The underlined word 'properties' in the fourth paragraph probably means _____. [     ] A. possessions B. qualities C. reactions D. symbols 4. What would be the best title for the passage? [     ] A. High-tech Products B. Nano Cups C. Nano Materials D. High-tech Research