单选题 Please make sure that the file of requested information is attached ______ to the document you send by mail.
  • A. secure
  • B. securely
  • C. securable
  • D. security
【正确答案】 B
【答案解析】[解析] 单词形态：副词 1．选项均为动词secure的不同形式。 2．空格内应填入副词来修饰动词attached，所以B为正确选项。