题目内容
在用K2Cr2O7标定Na2S2O3时, KI与K2Cr2O7反应较慢,为了使反应能进行完全,下列措施不正确的是:
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在碘量法中淀粉指示剂颜色变化正确的是:
碘量法是氧化还原滴定法中常用的方法之一。I2与 Na2S2O3的反应一般在____和____性溶液中进行。
淀粉指示剂最好临用前配制,不能放置,放置过久会使淀粉变质失效。
Listen to a short passage concerning digital education and fill in the missing information.This is the VOA Special English Education Report.We _____1______ a question from a listener in the West Bank about how American schools use _______2______ technology. There is not a simple answer. It depends on the subject and level of students, of course.But it also depends on the interest and ___3________ of the teachers, and the goals and budgets of the schools. Schools are almost all _____4_______ to the Internet. But some have more technology, and use it more, than others.For example, some schools use computers for ______5_______ like video conferencing, to bring the world into the classroom. And some classrooms _______6____________ things like a Smart Board, a kind of interactive whiteboard. Interactive whiteboards are large ______7_____ for presentations.They connect to a computer and can _____8______ by touch. They can be used for documents or writing or to _____9___ video. Some teachers are trying ____10_____ new ways to teach with devices like iPods and mobile phones. But educators say the most important thing, as always, is the ___11_____.
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