(2013·泉州一中期末)Close the door of fear behind you，and you ________ the door of faith open before you.

A．saw　　

B．have seen

C．will see

D．are seeing

以下血钾浓度为急性肾衰竭危险界限的是（）

A.血钾>4.5mmol/L

B.血钾>5.5mmol/L

C.血钾>6.5mmol/L

D.血钾>7.5mmol/L

E.血钾>8.5mmol/L