对于慢性肾衰竭时的心律失常，下列哪项是错误的（）

A.可由高钾血症引起

B.可因低钾血症引起

C.可由高钙血症引起

D.可有窦房传导阻滞

E.可有室性心动过速

The presentation layer is concerned with the（1） and semantics of the information exchanged between two systems. The processes in two systems are usually exchanginginformation in the form of character（2）numbers, and so on. The information should bechanged to bit （3） before being transmitted. Because different encoding systems, thepresentation layer is responsible for （4）between these different encoding methods. Thepresentation layer at the sender changes the information from its sender-dependent format into acommon format. The presentation layer at the receiving machine changes the common format intoits （5） dependent format.

（3）是（）

A.systems

B.characters

C.layers

D.streams