日照传感器有（ ）个同轴光电感应器对辐射进行自动连续观测。
A. 2
B. 3
C. 4
D. 5
使用暗筒式日照计需要每天在日落后换纸，如果是全日阴雨，无日照记录时可以不换。
A. 对
B. 错
How can Uber attract more customers according to Para.7?
A. By word of mouth
By professional drivers
C. By Uber Pool
D. By private car owners
How did Airbnb find the property owners willing to share their places?
A. By knocking on their doors one by one.
By taking inviting pictures of their homes.
C. By advertising on the social media.
D. By contacting them after knowing their information from Craigslist.
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