It is the interaction between people, rather than the events __ occur in their lives, __ is the main focus of social psychology.

A．that, that

B．that, which

C．which, which

D．that, what

患者，65岁，近来心悸，心电图可见提前出现的正常QRS波群，其前P波形态与窦性P波略不相同，其后有不完全性代偿间歇，诊断为（）

A.房性期前收缩

B.结性期前收缩

C.室性期前收缩

D.第二度Ⅰ型房室传导阻滞

E.窦性心律不齐