They are teachers and don’t realize _______ to start and run a company.

A．what takes it

B．what they take

C．what takes them

D．what it takes

男性，46岁。因心脏进行性扩大6年，曾住院诊断为扩张型心肌病，本次因气急加重，水肿明显1周来诊，门诊检查后疑有大量心包积液，下列哪项最支持此诊断

A．心电图示肢导联低电压

B．吸气时收缩压较呼气时降低20mmHg

C．心音弱

D．心界向两侧扩大