英语主动语态变被动语态题

1、an old man is helped cross the street by us.
2、an old man was helped cross the street by us.
3、jenny is seen by danny to come out of the classsroom.
4、jenny was seen by danny to come out of the classsroom.
5、the e-mail is often send to danny by me.
6、an e-mail was sent to danny by me yestaday.