在同一导联上室早形态不同，且配对间期不等时称为( )
A．偶发室早
B．插入型室早
C．频发室早
D．RonT室早
E．多源性室早
参考答案：E
I was out of town at that time, so I don’t know exactly how it ______.
A．was happening
B．happened
C．has happened
D．happens
