题干

观察《中国古代丝织业中心分布变迁图》,依据图中信息,可以得出的结论是(    )

A:古代丝织业的中心呈现由北至南转移的趋势

B:汉代丝织业中心由都城长安向全国各地辐射

C:唐宋时期的丝织业是发展最快的手工业部门

D:元至清朝苏州、南京等地也成为丝织业中心

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A,D

同类题5

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    Flying devices called drones(无人机) may be one of the most important technologies of the future.

    The number of jobs for people who know how to design, build and control them is increasing. Because of this increase, several U.S. universities have started offering degrees in unmanned aircraft systems, or UAS.

    One of these universities is the University of Washington in Seattle. Ward Handley is seeking a master's degree in UAS at the university. When the drone program first began, he did not think it was a good idea. “Drones can be used to invade privacy(侵犯隐私).” He said. But later, Handley changed his opinion. He said, “I think there are good enough purposes for them.”

    The FAA (the part of the U.S. government that controls air travel and traffic) is creating new rules to control the use of drones, however. A new law requires drone owners to register(登记) their drones. People who do not register their drones could face fines of up to US$20,000.

    The new rules may also present problems for students. One problem is finding a legal place to fly.

    Students at Blue Mountain Community College fly inside the college gym. In Seattle, University of Washington students test their drones in a big room.

    Christopher Lum, a scientist at the University of Washington, helps students explore how drones can safely share the sky with regular aircraft. Lum explained why they test drones inside a building, “We need to register our aircraft and get permission to fly outside. That process can take months.”

    At this time, Kansas State University is the only school with permission to offer unmanned aircraft flight classes to students outside. The FAA selected Kansas State University and 15 other universities to be part of a national research group.

    Lum and some of his students recently moved their research to Australia. Australia has fewer rules limiting drones. A professor at Western Washington University also took his department's drones to Canada for the same reason.