信封 :envelopeRelative explainations:Examples:1. 这个信封封得很严实。

The envelope was firmly sealed.2. 寄信前，他在信封上写上地址。He addressed the envelope before mailing the letter.3. 信封内装有几份附件。There are several enclosures in the envelope.4. 他用蒸汽把信封上的邮票揭下来。He steamed the stamp off the envelope.5. 我用了一个邮资已付的信封。I use a prepaid envelope.6. 他把邮票贴在信封上。He glued a stamp onto the envelope.7. 信封（的封口）没粘住.The (flap of the) envelope was unstuck.8. 这个信封开了.This envelope has come unstuck.