The color red often means danger --- and by paying attention, accidents can be prevented. At railroad crossings, flashing red fights warn cars to stay back. A red light at a traffic crossing tells cars to stop, so they don't run into other cars. In the future, the color red also may help prevent danger at construction sites. Thanks to new work by engineers, bridge supports --- or other kinds of materials --- could one day contain a color-changing material. It will turn red before a structure collapses or falls apart. The secret behind the color-changing material is a particular type of molecule . Molecules come in all shapes and sizes, and make up everything you can see, touch or feel. How a molecule behaves depends on what kinds of atoms it contains, and how they're held together. To get a rough picture of one way atoms are held together in a molecule, imagine you and your friends standing in a large circle, holding hands. Each person represents one atom, your clasped hands represent the bond, and the entire circle represents a molecule. The molecule being used to turn the material red is called mechanophore . When one chemical bond in the mechanophore molecule breaks, the rest of the molecule turns red. There is a way to get rid of~ the red color: light. When a bright light is shone on the mechanophore, the broken bond is fixed and the red color disappears. This "self-healing" may be a problem for engineers who want to use the color-changer in big construction projects that will be outside, in the sunlight. And if bright light keeps the red color from appearing, then the mechanophore's warning system will be useless. Scientists still have a lot of work to do before the color-changing molecules can be used outside the lab. If mechanophore can be used in the real world, they are suggested to be employed in a new kind of paint. What can make the mechanophore's warning system ineffective? A) Paints B) Water C) Poor building materials D) The bright light
D
The bicycling craze came in when we were just about at the right age to enjoy it. At first even "safety" bicycles were too dangerous and improper for ladies to ride, and they had to have tricycles. My mother had (I believe) the first female tricycle in Cambridge; and I had a little one, and we used to go out for family rides, all together; my father in front on a bicycle, and my poor brother Charles standing miserably on the bar behind my mother. I found it very hard work, pounding away on my hard tyres; a glorious, but not a pleasurable pastime. Then, one day at lunch, my father said he had just seen a new kind of tyre, filled up with air, and he thought it might be a success. And soon after that everyone had bicycles, ladies and all; and bicycling became the smart thing, and the lords and ladies had their pictures in the papers, riding along in the park, in straw hats. My mother must have fallen off her bicycle pretty often, for I remember seeing the most appalling cuts and bruises on her legs. But she never complained, and always kept these accidents to herself. However, the great Mrs. Phillips, our cook, always knew all about them; as indeed she knew practically everything that ever happened. She used to draw us into the servants' hall to tell us privately: "Her Ladyship had a nasty fall yesterday; she cut both her knees and sprained her wrist. But don't let her know I told you." So we never dared say anything. Similar little accidents used to occur when, at the age of nearly seventy, she insisted on learning to drive a car. She never mastered the art of reversing , and was in every way an unconventional and terrifying driver. Mrs. Phillips used then to tell us: "Her Ladyship ran into the back of a milk-cart yesterday; but it wasn't much hurt"; or "A policeman stopped her Ladyship because she was on the wrong side of the road; but she said she didn't know what the white line on the road meant, so he explained and let her go on." Mrs. Phillips must have had an excellent Intelligence Service at her... How did the writer feel about tricycles? A) They were not as fast as bicycles. B) They were safer and more convenient for women. C) They were very hard to ride. D) They were not proper for women to ride.
C
Q: Macao is only forty miles from Hong Kong and it is easy to reach. You can get there by sea. It is an interesting place and it had a long history. Macao is part of China and most people living there are Chinese. The first Europeans to go to Macao came from Portugal . More than four hundred years ago the Portuguese went there to trade with China. Some settled and made their homes there. They built strong forts(,) to guard the city and the harbor. They also built churches, schools, hospitals and other places. Slowly the city grew. People from many countries came to live and work in Macao. Today many people visit Macao. Some only go there to watch dog-racing or motor-racing or to gamble with their money. But Macao is a quiet and peaceful place. It is pleasant just to walk around and look at old buildings and forts. You feel you are back in the old days. Of course, some of the buildings are now in ruins. The Church of St. Paul has only the front wall with many steps leading up to it. But it is still interesting to see. When you are hot and tired, there are small cool gardens to rest in. when you are hungry, there are good restaurants with many kinds of food. Nearby there are some islands, which are also nice and are easy to get to. There is certainly a lot to do in Macao. Where will you have a break when you feel tired? A) In good restaurants. B) In small cool gardens. C) On some islands. D) In beautiful parks.
A: B
Q: Norm Pethrick, a 36-year-old man in Australia's northern city Darwin, was praised on Thursday for jumping onto a crocodile's back to save his wife Wendy at Litchfield National Park, a popular tourist spot southwest of Darwin, a local newspaper reported. Ms Pethrick was standing on a river bank Wednesday afternoon when the saltwater crocodile lunged , locking its jaws on both her legs as it tried to drag her underwater. Norm Pethrick, who with his wife had been collecting water, immediately went to help her. He jumped onto the back, poked the eyes of the crocodile and finally got his wife free. Ms Pethrick was later taken to Royal Darwin Hospital for a medical treatment. The doctors said she was suffering eight puncture wounds in her right leg, a puncture wound in her left leg and a serious cut to one of her fingers. "This could have been a fatal and tragic situation," said the general manager of Royal Darwin Hospital (RDH), Dr Len Notaras, according to a local report. He said Ms Pethrick was saved by her husband's "quick and diligent actions". Dr Notaras also said she would remain in hospital for three to four days and have an operation to clean the wounds, which are easy to get infected because of bacteria on the teeth of the crocodile. This passage is most likely to be found in _ . A) a travel guide B) a textbook C) a newspaper D) a novel
A: C