题型:问答题 It's not easy to learn English well. _____ as much as possible is necessary.A. Having readB. Read C. Reading D. To have read 查看答案
题型:问答题 有关触发活动的描述,不正确的是()A.触发活动是指动作电位后产生的除极活动,也称为后除极B.若后除极的振幅增高并抵达阈值,便可引起反复激动C.触发活动多发生于动作电位的2相D.触发活动亦可导致持续性快速性心律失常E.可见于局部出现儿茶酚胺浓度增高、心肌缺血再灌注、低血钾、高血钙及洋地黄中毒时 查看答案