As is known ( to us all ), ⋯ = It is known (to us all) that ⋯2
It seems that sb
seems to⋯It appears (to sb) that ⋯=sb
appears to⋯3
It (so)happened that sb
happened to⋯4
There is/are⋯
There seems to be⋯There happened to be⋯There must have been⋯There is going to/will be⋯5
Sth occurr ed to sb It (suddenly) occurred to sb t hat ⋯It never occurred to sb that⋯ = It didn ’toccur to sb that⋯6
It is said / reported that sb
⋯ = sb / sth is said / reported to do⋯It is believed that sb
⋯ = sb / sth is believed to do⋯⋯7
It is no good / use doing ⋯ They think / consider / feel it no use / good doingIt is likely thatsb
⋯ = sb / sth is likely to do ⋯It is possible / probable that sb
It is hard to imagine /say / believe⋯It is n