A custom JSP tag must be able to support an arbitrary number of attributes whose names are unknown when the tag class is designed.  Which two are true？ （）

• A、 A  element in the echo tag LTD must have the value JSP
• B、 The echo tag handler must define the setAttribute （String key， String value） method
• C、 The true element must appear in the echo tag TLD
• D、 The class implementing the echo tag handler must implement the javax.sevlet.jsp.tagext.IterationTag interface
• E、 The class implementing the echo tag handler must implement the javax.sevlet.jsp.tagext.DynamicAttributes interface