心脏正常窦性心律的起搏点是() A.左心房 B.窦房结 C.房室结 D.右心房 E. 发布时间:2019-03-04 18:56 │ 来源:www.tikuol.com 题型:单项选择题 问题: 心脏正常窦性心律的起搏点是()A.左心房B.窦房结C.房室结D.右心房E.心室
题型:单项选择题 —No one was prepared for the teacher's questions.—We________read the lesson yesterday evening.[ ]A. must have B. could have C. should have D. might have 查看答案
题型:单项选择题 炎热的夏天,人站在海水中感到凉爽,而当赤脚走在沙地上时却感到烫脚,这主要是因为______;已知水与沙子的比热容之比是4:1,质量相等的水和沙子吸收相同的热量,升高的温度之比是______. 查看答案