重点讲解：
1. be considered to do sth.
被认为是；
eg. She is considered to lack experience.
人们认为她经验不足。
eg. Most loess is considered to be an eolian deposit.
大多数黄土被认为是一种风成沉积。
2. be belived to do sth.
被认为；
eg. She was believed to have the gift of prophecy.
据信她有预言的天赋。
eg. These creatures were believed to have come from outer space.
据信这种生物来自外太空。
3. mount on
安装；安置；裱；
eg. Her husband mounts the work on velour paper and makes the frame.
她丈夫把作品装裱在绒纸上，并制作了画框。
eg. The support for the fence is mounted on an extension to the table.
篱笆的支撑部分安装在桌子延长出的地方。