Please feel free to remove inapplicable items for your PR.
[y] The PR title starts with [$CATEGORY] (例如[bugfix]修复bug，[new]添加新功能，[test]修改测试，[rm]删除旧代码)
[y] Changes are complete (i.e. I finished coding on this PR) 修改完成才提PR
[y] All changes have test coverage 修改的部分顺利通过测试。对于fastnlp/fastnlp/的修改，测试代码必须提供在fastnlp/test/。
[y] Code is well-documented 注释写好，API文档会从注释中抽取
[y] To the my best knowledge, examples are either not affected by this change, or have been fixed to be compatible with this change 修改导致例子或tutorial有变化，请找核心开发人员
Description：Fixed the bug of elment value
Main reason: 针对会议所提出的要求进行修改
Checklist 检查下面各项是否完成
Please feel free to remove inapplicable items for your PR.
Changes: 逐项描述修改的内容
@修改过这个文件的人 @核心开发人员