【单选题】Watch the video. Choose the best alternative title for it.
A.
a. How Crowdsourcing Led Us to an Ancient Tomb
B.
b. Journeying on Horseback Across the Burkhan Khaldun
C.
c. Lessons from a Crowdsourcing Failure
【判断题】一批轴要进行粗加工和精加工,通常应至少分成两道工序
【单选题】近代技术上曾经出现过( )次技术体系更迭。
【简答题】Watch the video. Fill in the blank and tranlate it into Chinese.
【简答题】A.She is quite young. B.She is middle-aged. C.She is 40 years old. D.She is of the retirement age.