题目内容：
The project of railway switch snow protection system based on the principle of the air umbrella, was the second prize winner of the:
A.the First China-US Young Maker Competition
B.the 10th National Competition of Transport Science and Technology for Students
C.the 10th National University Student Social Practice and Science Contest on Energy Saving & Emission Reduction
D.the 6th National Mechanical Innovation Design Competition
参考答案：