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 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
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