y=5x4=x45,
∴y′=(x45)′=45x-15,
故选C.
Please keep _________ while I take your photograph.
A.still
B.calm
C.quiet
D.silent
房间隔缺损的典型心电图表现为
A.电轴右偏,不完全性右束支传导阻滞
B.右心室肥厚
C.P波高尖
D.P-R间期延长
E.右心房与右心室肥大