下面的短文有15处空白，请根据短文内容为每处空白确定1个最佳选项。
第6部分：完形填空(第51-65题，每题1分，共15分) 下面的短文有15处空白，请根据短文内容为每处空白确定1个最佳选项。 Seeting Red Means Danger Ahead The color red often means danger–and by paying attention, accidents can be prevented. In the future, the color red also may help ________ (51) danger at construction sites. Thanks to new work by engineers, bridge supports - or _______ (52) kinds of materials -- could one day contain a color-chan-ging material. It will turn red ________ (53) a structure collapses or falls apart. The secret _______ (54) the color-changing material is a particular type of molecule (分子). A molecule is a group of atoms(原子)held together by chemical bonds. Molecules come ______ (55) all shapes and sizes, and make up _______ (56) you can see, touch or feel. How a molecule behaves depends on ________ (57) kinds of atoms it contains, and how they re held together. When a polymer (聚合物) containing a color-changing molecule called a mechanophore (机械响应性聚合物) is about to break, it produces a ________ (58). When a polymer with mechanophore molecules becomes "injured" or ________(59), one of the mechanophore bonds _______ (60) and the material turns red. "It s a really simple detection method," says Nancy Sottos, one of the scientists who worked on the project. Sottos and her team tested the color-changing polymers in their lab. The test _________ (61) proved encouraging. 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 ________ (62). This "self-healing" may be a problem for engineers. They need to use the color-changer in big construction projects that will be ________ (63), in sunlight. And sunlight will make the mechanophore s warning system ________ (64). Sottos and her fellow scientists still have _________ (65) work to do before the color-changing molecules can be used outside the lab. 51. A. throw B. prevent C. create D. keep 52. A. other B. another C. the other D. others{来源：考{试大} 53. A. until B. although C. after D. before 54. A. on B. behind C. under D. down 55. A. for B. in C. from D. at 56. A. nothing B. anyone C. someone D. everything 57. A. why B. how C. what D. where 58. AI color B. trouble C. sound D. time 59. A. strong B. soft{来源：考{试大} C. weak D. hard 60. A. closes B. breaks C. increases D. burns 61. A. results B. rules C. tools D. methods 62. A. repairs B. controls C. finishes D. disappears 63. A. inside B. beside C. outside D. above 64. A. dangerous B. useless C. helpful D. important 65. A. a pair of B. a type of C. a lot of D. a part of