At night, the solar energy (stored as vast quantities of heat in city buildings and roads) is slowly released into the city air. Additional city heat is given off at night (and during the day) by vehicles and factories, as well as by industrial and domestic heating and cooling units. The release of heat energy is retarded by the tall vertical city walls that do not allow infrared radiation to escape as readily as does the relatively level surface of the surrounding countryside. The slow release of heat tends to keep nighttime city temperatures higher than those of the faster-cooling rural areas.
The word "retarded" in the passage is closest in meaning to
B. added to
C. made possible
D. slowed down
The release of heat energy is retarded by the tall vertical city walls that do not allow infrared radiation to escape as readily as does the relatively level surface of the surrounding countryside.
The tall vertical city walls are doing something to the heat energy because they do not allow infrared radiation to escape.
总而言之就是city wall对heat energy做了点什么以防止radiation escape。这个句子里比较有意思的就是do not allow，现在再回头去看题目选项给出的这些词汇，added to和made possible显然在意思上都是和not allowed有冲突的，可以先排除掉，剩下的diguised不好判断，heat energy能不能被disguised不好说，但放在这里显然意思上不太搭，跟整个句子关系不大。这样一来选项D显然看上去就顺眼多了，不让infrared radiation逃脱所以要slow down一下heat energyd的释放也是比较符合逻辑关系的。正确答案也的确就是D。
Several dinosaur fossil localities preserve coprolites. Coprolites yield unequivocal evidence about the dietary habits of dinosaurs. Many parts of plants and animals are extremely resistant to the digestive systems of animals and pass completely through the body with little or no alteration. Study of coprolites has indicated that the diets of some herbivorous dinosaurs were relatively diverse, while other dinosaurs appear to have been specialists, feeding on particular types of plants. The problem with inferring diets from coprolites is the difficulty in accurately associating a particular coprolite with a specific dinosaur.
The word "unequivocal" in the passage is closest in meaning to