一、据说… It is said (that)从句

　　据报导… It is reported (that)从句

　　大家都知道… It is known (that)从句

　　一般认为… It is thought (that)从 句

　　一般预料… It is expected (that)从句

　　据估计… It is estimated (that)从句

　　一般相信… It is believed (that)从句

　　例：

　　1、It’s reported that some nuclear radiation from Fukushima of Japan has gone into the sea. 据报道，部分日本福岛核辐射已经进入海洋。

　　2、It's known that Chongqing is a mount city. 众所周知，重庆是座山城。

　　二、表达”某事发生多久了?” 常用以下句型.

　　1、(短暂性动词的)一般过去时.

　　2、延续性动词的现在完成时.

　　3、时间段 has passed since 从句(短暂性动词的一般过去时)

　　4、It’s 时间段since 从句(短暂性动词的一般过去时)

　　例：他爷爷去世20年了。

　　1、His grandpa died 20 years ago,

　　2、His grandpa has been dead since 20 years ago. (for 20 years )

　　3、Twenty years has passed since his grandpa died.

　　4、It’s 20 years since his grandpa died.