1 Who has bought ....?
I have.
2 Who bought ...?
They did.
3 Who is going ...?
We are.
4 Who has always wanted ...?
They have.
5 Who has worked....?
They have.
6 Who worked..?
They did.
7 Who was ...?
They were.
8 Who has always been...?
They have.
9 Who lives....?
His parents do.
10 Who has always lived....?
His parents have.