IV
1.their/your
2.his/her
3.our/their
V
1.it
2.there
3.there
4.it
5.there
VI
1.more and more people spend their holidays aboard every year
2.there are lots of queues at the passport controls at peak times
3.plane delays can be the result of take offs and landings
4.members of the cabin crew will make your flight more comfortable and pleasant
5.it is such a relief to get home with all your luggage