1、it is well-known to us that……（我们都知道……）==as far as my knowledge is concerned, …（ 就我所知…）。
2、recently the problem of…… has been brought into focus. ==nowadays there is a growing concern over ……（最近……问题引起了关注）。
3、nowadays（overpopulation）has become a problem we have to face.（现今，人口过剩已成为我们不得不面对的问题）。
4、internet has been playing an increasingly important role in our day-to-day life. it has brought a lot of benefits but has created some serious problems as well.（互联网已在我们的生活扮演着越来越重要的角色，它给我们带来了许多好处但也产生了一些严重的问题）。