D
   Engineers have developed a vegetable-picking robot. Although the robot is nowhere near as fast as a human worker, it shows how the use of robotics in agriculture might be expanded, even for crops which are particularly hard to harvest mechanically. Crops, such as potatoes and wheat, have been harvested mechanically on a large scale for decades, but many other crops resist automation. The iceberg lettuce (生菜) is one such crop. Although it is the most common type of vegetables in the UK, iceberg lettuce is easily damaged and grows relatively flat to the ground, presenting a challenge for robotic harvesters.
   The vegetable-picking robot--- the Vegebot--- has a computer vision system and a cutting system. The overhead camera on the Vegebot will take a picture of the lettuce field. Then it will identify all the lettuces in the picture.
   For each lettuce, it will classify whether it should be harvested or not. A lettuce might be rejected because it’s not yet mature, or it might have a disease that could spread to other lettuces in the harvest. Finally, the robot will cut the lettuce from the rest of the plant without damaging it.
A second camera on the Vegebot is positioned near the cutting blade (刀刃), and helps ensure a smooth cut. The researchers were able to adjust the pressure in the robots gripping (夹持) arm so that it could hold the lettuce firmly enough without dropping it, but not so firmly because it may damage the lettuce. The force of the grip can be adjusted for other crops.
In the future, robotic harvesters could help address many problems in agriculture. At present each field is typically harvested once, leaving the rest wasted. However, the new robotic harvester could be trained to pick only ripe vegetables and perform multiple passes on the same field, returning at a later date to harvest the vegetables that were unripe during previous passes. The researchers hope it could compete with a human worker one day after they improve its efficiency. And they think it has lots of potential in agri-tech.
12. The iceberg lettuce is mentioned in paragraph 1 mainly to show _____.
A. the characteristics of the iceberg lettuce    
B. the difficulties of harvesting certain crops mechanically   
C. the differences between common crops and the iceberg lettuce     
D. the directions in present research into agricultural development
13. What’s the function of the overhead camera on the Vegebot?
A. To record the cutting process.                   B. To measure the size of one field.
C. To find the harvest target accurately.             D. To assist in cutting the crop smoothly.
14. What can we know about the Vegebot from the last paragraph?
A. It has been put on the market.                   B. It has gained favor with farmers.
C. It will soon replace human workers.              D. It can help reduce food waste during harvest.
15. Where does the text probably come from?
A. A science magazine.      B. An advertisement.       C. A research plan.     D. A business report.
                                             12-15BCDA