题目

听材料，回答问题。 （1） What time do the dancers need to arrive? A . 5: 00 pm. B . 6: 00 pm. C . 7: 00 pm. （2） What does Mrs Hannah do? A . She answers all questions. B . She is in charge of the dresses. C . She controls the music and lights. （3） What clothes should volunteers wear for the show? A . Black clothes. B . White clothes. C . Red clothes. （4） Why does Tina have to stay longer today? A . She needs to practice more. B . She came late today. C . There is a change in her part.如图为人体内控制某块肌肉收缩的反射弧模式图，a、b为灵敏电流计F的两个微型电极，置于神经细胞B和神经细胞D的膜外．请据如图分析：（1）如果d处给一适当的刺激，则d处细胞膜外的电位变化是 ，电流计指针发生两次方向 （相反/相同）的偏转．（2）在反射弧中，决定神经冲动单向传导的结构是 ．（3）若从a处切断神经纤维，刺激d处，效应器 （能/不能）发生反应．