Ответ: в объяснение

Объяснение: 1) Who has just had lunch in a cafe?

What have we just had in the cafe?

Where have we just had lunch?

2) Whose books has mother put into the bag?

What has mother put into the bag?

Where has mother put my books?

3) Who has known you for seven years?

Whom have I known for seven years?

For how many years have I known you?