She is so helpful that she is always ready to help people in trouble. Which of the following is correctfor the underlined word in the sentence?

A．/'tr37bl/

B．/'tra7bl/

C．/'trKbl/

D．/'trbl/

慢性肾衰竭常见的电解质紊乱是（）

A.高血钙

B.低血钙

C.高血镁

D.低血镁

E.高血钾