As summer vacation is come soon, my classmates are trying very hardly to get train tickets to go home. But I have made up my minds to spend the vacation far from home for first time in my life. My parents have agreed to visiting me, and I will have a different vacation. When they come here, I will show they around my university and the city as well as. I have decided to buy them some nice gifts. It will be a big surprise for them. My parents had done a lot for me, and I think it is high time that I did anything special to express their thanks.

关于强心苷，哪项错误（）

A.有正性肌力作用

B.有正性心肌传导功能

C.有负性频率作用

D.安全范围小

E.用于治疗心衰，也可治疗室上性心动过速