题目Word 2010 文档默认的文件的扩展名是 ( )A. .txtB. .docxC. .exeD. .htmlE. .pptWord 2010 文档默认的文件的扩展名是 ( )A. .txtB. .docxC. .exeD. .htmlE. .ppt题目解答答案B. .docx