求如图所示的交变电流的有效值，其中每个周期的后半周期的图象为半个周期的正弦曲线（ 发布时间：2017-07-31 00:19 │ 来源：www.tikuol.com 题型：选择题 问题： 求如图所示的交变电流的有效值，其中每个周期的后半周期的图象为半个周期的正弦曲线（ ）A．5AB．5AC．5/2AD．/2A
题型：选择题 用方框中所给单词的适当形式填空。direct, lead, wonder, certain, politewrite, trouble, park ,easy, lend1. We had a _______time in Dalian during the vacation.2. The boy went __ _ up to his mother when she came in.3. It's _______to talk to old people loudly.4. He will _______ die, if you don't get a doctor.5. Our English teacher _ into the new lesson with an English song.6. E-mail English is fun, you can learn it _______ by yourselves.7. These days he is unhappy, because he has a lot of _ in studying.8. E-mail English is a new kind of _______ English that is being used to save time.9. Thank you for_______ me your book.I0. Look at the sign. It says, "No __ ." 查看答案
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