我国第一部真正意义上针对建设工程安全生产的行政法规是()
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杆件变形的基本形式：____、_____、______、_______四种。
By mentioning the study of IEEE Spectrum, the author intends to______.
A. prove that the danger of using cell-phone on plane does exist
B. advocate that all airlines should provide Wi-Fi service
C. explain how cell-phone may endanger a flight
D. inform. readers of which devices should be allowed to use on plane
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