tiìm x biết x.(x-2)+28=(x+2)^2 +12 

Change the following sentences in passive voice

1.  They were planting trees at 5 p.m yesterday.

2 She was painting a picture when I came yesterday.
3. He was typing a letter this time yesterday

4. Tom wrote that letter
5.  They built a stadium near the river
a stadium

6.  They bought their car in 1990

7 She will write a letter to her teacher tomorrow.