您要查找的是不是：
- Have you stuck down the back of the envelope? 信封背面开口处贴牢了吗？
- He steamed the stamp off the envelope. 他用蒸汽把信封上的邮票揭下来。
- His figure looks very funny in the concave mirror. 他的样子在凹镜里显得非常可笑。
- An indented or concave surface or area. 凹陷，洼地凹的表面或地区
- He glued a stamp onto the envelope. 他把邮票贴在信封上。
- As he picked up the envelope, a key dropped out. 他拣起信封时，一把钥匙掉了出来。
- As she picked up the envelope, a key dropped out. 她拾起信封时，一把钥匙掉了出来。
- Put a stamp on the envelope, will you? 在信封上贴张邮票，好吗？
- He stuck a stamp on the envelope. 他在信封上贴上邮票。
- She opened the envelope with her fingertips. 她用指尖弄开了信封。
- The envelope's seal was torn open. 信封封缄被撕开了。
- The (flap of the) envelope was unstuck. 信封(的封口)没粘住。
- There are several enclosures in the envelope. 信封内装有几份附件。
- concave envelope 凹包
- An envelope or wrapper for mail. 封套，信封为邮寄而制的信封或封套
- Just as a double convex lens enlarges, so a double concave lens reduces. 正象双凸透镜可以放大那样，双凹透镜也可以缩小。
- A good way to remove a stamp from an envelope is to soak it off. 从信封上取下邮票的一个好办法就是用水把它泡下来。
- I enclose a stamped addressed envelope for your reply. 兹附上贴有邮票并写好地址的回邮信封。
- He ripped off one end of the envelope and pulled out the letter. 他撕开信封的一端，抽出里面的信件。
- A concave molding with a cross section that approximates a quarter circle. 飞檐的凹圆线脚截面近于九十度弧的凹线脚
