A:电磁打点计时器和电火花打点计时器都用交流电
B:两种打点计时器的打点频率与交流电的频率一样
C:电磁打点计时器在交流电频率为50Hz时,两个打点间隔时间为0.1s
D:电火花计时器在纸带上打点是靠振针和复写纸
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根据短文内容填空。
Jane White is an American girl. She is fifteen. She is a middle school student. Her father is Bill White and her mother is Joan White. Her brother, Bob, is a student, too. He is in a black coat and Jane is in a red sweater.
阅读图文材料,完成下列要求。
中国古典园林强调人与自然的和谐统一,体现了中华民族对自然和美好生活环境的向往与热爱。图4为我国某类古典园林的主要分布区域,明清时期该区域经济繁荣,园林建设蔚然成风。