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[主观题]
When he was in the countryside, he ______ visit the poor peasants.A.used toB.was used toC.
When he was in the countryside, he ______ visit the poor peasants.
A.used to
B.was used to
C.is used to
D.had used to
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When he was in the countryside, he ______ visit the poor peasants.
A.used to
B.was used to
C.is used to
D.had used to
第6题
突触后抑制是由抑制性中间神经元的活动引起的,这些抑制性中间神经元兴奋时.其轴突末梢释放(),在()产生抑制性突触后电位,致使突触后神经元的活动受到抑制。
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