— Who broke the toy car?    

— It ______ Alex. He likes to throw things here and there. [ ]

A. may be

B. must be

C. can't be

D. is

患者男性，24岁，反复胸闷气短4年，近1周加重，端坐时即感胸闷，伴咳嗽，下肢水肿，肝大，超声心动图示心脏扩大，室壁变薄，EFl0%，二尖瓣、三尖瓣中度反流，既往无其他病史。

该患者心电图可见的表现

A．ST段压低

B．T波平坦、双相或倒置

C．有时可见病理性Q波

D．一度至三度房室传导阻滞均可发生

E．心律失常不常见