第二题将下列句子改为被动语态,咋写,

1.The telephone was invented by Bell in 1876.
2.He was laughed at by all the people.
3.She was seen by him in the shop yesterday.
4.I was told not to be late by Mother.
5.He was heard sing in his room just now.
6.The old people should be taken care by us.
7.He was made to work 12 hours a day.