题目: Had she _____ her promise, she would have made it to Yale University. [ ]A. looked up to B. lived up toC. kept up with D. come up with 答案: 答案:B
题型:单项选择题 膜内外Na+和K+浓度梯度的维持是由于A.膜在安静时对K+通透性大B.膜在兴奋时对Na+通透性大C.Na+和K+易化扩散的结果D.膜上Na+-K+泵的作用E.膜上ATP供能的作用 查看答案
题型:单项选择题 在正常工作时,全权数字式发动机控制(FADEC)系统:().A.只是一个飞机电气系统 B.如果飞机供电故障时,是电瓶 C.在大于10%N2时,自我供电 D.是飞机电气系统或在应急时自我供电 查看答案