Question

combine the following sentences with 'when'.

1 .the buses began to move.the passengers rushed to the bus station.

combine the following sentences with 'who'.

 1.the girl is my sister.i'm talking to the girl.

2.this is the chair .the carpenter repaired it last week.

also explain how to combine.

Answer 1

the buses began to move when the passengers rushed to the bus station
i'm talking to the girl who is my sister
this is the chair which the carpenter repaired last week.
 
after arranging the sentence must be meaningful. following this we can arrange them.

Answer 2

the buses began to move when the passengers  rushed to the station
the girl is my sister who i am talking to
this is the chair which was repaired by the carpenter last week