It is estimated that... 据估计，有人估计

　　It is estimated that... 有人指出，人们指出

　　It is pointed out that... 有人推荐，有人建议

　　It is proposed that... 有人提出

　　It was told that... 有人曾经说

　　It was first intended that... 最初就有这样的想法

　　It will be said that... 有人会说

　　It will be seen from this that...

　　由此可见，因此可知

　　It was noted above that... 前面已经指出

　　It must be admitted that... 必须承认，老实说

　　It has been illustrated that... 据图示，据说明

　　It is stressed that... 有人强调说

　　It is stressed that... 有人列举出了

　　It can not be denied that... 无可否认

　　It can be said without exaggeration that... 可以毫不夸张的说

　　It is sometimes asked that...人们有时会问

　　It was felt that... 有人认识到了

　　It is universally accepted that... 人们普遍认为

　　It is unanimously agreed that... 大家一致同意

　　It is alleged that... 据说

　　It is calculated that... 据计算

　　It has been proved that... 已经证明

　　It has been found that... 人们已经发现

　　It is still to be hoped that... 我们仍然希望

　　It is well-known that... 众所周知，大家都知道

　　It should be realized that... 我们应该认识到……