My neighbor’s children love playing hide-and-seek as other children do ，but everybody had imagined that the game they played themselves last week would be reported in the local newspaper. One afternoon, they are playing at the street comer. Paul, only five year old, hid and locked himself in a storage mailbox in accident His sister, Nancy, heard his cries and realized what had happened, so she immediately asked a mailman open the metal door. Paul was free ，but he had such bad a scare that he could not stop cry. The mailman told him that next time he wanted to hide in a mail box, he should remember to put the stamp on himself. When he heard that ，Paul burst into laughing.

高钾血症时机体可出现（）

A.碱中毒

B.易发生洋地黄中毒

C.心动过缓

D.神经-肌肉兴奋增强

E.心电图出现U波