These services are widely used. Turnitin.com,for example, says it is used in more than one hundred countries and examines more than one hundred thirty thousand papers a day.
VOA : special.2009.04.16
英汉双解词典包含3185865条英汉词条，基本涵盖了全部常用单词的翻译及用法，是英语学习的有利工具。