房室交界处传导速度较慢的生理意义在于
A.有效防止出现期前收缩
B.有利于心房或心室同步收缩
C.有利于心室充盈和射血的交替
D.有效避免出现完全强直收缩
参考答案:C
We all know that doing morning exercises ______. [ ]
A. is good for our healthy
B. are good for our healthy
C. are good for our health
D. is good for our health
下列何部件在地面不起作用().
A.35°F控制器
B.冲压系统控制器
C.后溢流后门
D.CPC