【单选题】【消耗次数：1】
设输入信号ui为负半周，经V1倒相放大后，加到V2和V3管基极的是正半周信号，功放管V2导通，V3管截止。负载RL上获得正半周信号。当输入波形ui为正半周时，负载（扬声器或者R5）获得负半周信号。如此两管轮流工作，在负载上可以得到完整的信号波形。
①
正确
②
错误
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相关题目
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设无向图G1 = áV1, E1?, 其中, V1 = {v1, v2, v3, v4, v5}, E1 = {(v1, v2), (v2, v3), (v3, v4), (v3, v3), (v4, v5)}，则v2的邻域 N(v2)为：
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{v1, v2, v3}；
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{v1, v3}；
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{v1, v2, v3, v4, v5}；
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{v2}。
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{v1, v2, v3}；
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{v1, v3}；
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{v1, v2, v3, v4, v5}；
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{v2}。
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设有向图D = áV, E?, 其中 V={v1, v2, v3, v4, v5}, E={áv4, v1?, áv1, v1?,áv1, v2?,áv1, v3?, áv3, v1?, áv5, v3?}，则v1的邻域 N(v1) =
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{v3, v4}；
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{v2, v3,v4}；
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{v1, v2, v3, v4}；
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{v2,v3}。
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设有向图D = áV, E?, 其中 V={v1, v2, v3, v4, v5}, E={áv4, v1?, áv1, v1?,áv1, v2?,áv1, v3?, áv3, v1?, áv5, v3?}，则v1的闭邻域 N(v1) =
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{v3, v4}；
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{v2, v3,v4}；
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{v1, v2, v3, v4}；
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{v2,v3}。
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设有向图D = áV, E?, 其中 V={v1, v2, v3, v4, v5}, E={áv4, v1?, áv1, v1?,áv1, v2?,áv1, v3?, áv3, v1?, áv5, v3?}，则v1的先驱元集G -(v1) =
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{v3, v4}；
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{v1, v3,v4}；
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{v1, v2, v3, v4}；
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{v3, v4}；
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{v1, v3,v4}；
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{v1, v2, v3, v4}；
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{v2,v3}。
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已知有向图G=(V,E)，其中V={V1,V2,V3,V4,V5,V6,V7}，E={V1,V2V1,V3V1,V4V2,V5V3,V5V3,V6V4,V6V5,V7V6,V7}，G的拓扑序列是（ ）。
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V1,V3,V4,V6,V2,V5,V7
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V1,V3,V2,V6,V4,V5,V7
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V1,V3,V4,V5,V2,V6,V7
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increasing use of abbreviation
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increasing use of open compounds
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increasing use of conversion
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Italian, Latin, Greek
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French, Germanic, Greek
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Germanic, Italian, French
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正确
②
错误
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