When you do an experiment, it is important that you have ____ patience to observe and record ___

whole process of the experiment    [ ]

A. a ; a 

B. the; the      

C. the ; a

D. /; the

窦性心律不齐的心电图表现为（）

A.突然出现明显延长的PP间距，长PP间距不是短PP间距的整数倍

B.同一导联上窦性PP间距相差>0.12s

C.PP间距逐渐缩短，继而出现一长PP间距，尔后PP间距又重复以上规律

D.不同导联上PP间距相差>0.12s

E.突然出现明显延长的PP间距，长PP间距是短PP间距的整数倍