This text is for questions 13 to 16.

    If digging a hole doesn't work, you can collect water vapor rising from damp ground and turn into water. It is a slow, tough process so it is worth trying only as a last resort Do the job in early morning, because you need the heat of the sun to evaporate the water.

1. Locate a site that is damp beneath the surface but that is in full sunlight Dig a hole about 60 cm deep and wide. Place the container in the hole and put one end of the tube in it Drag the other end out of the hole.
2. Cover the hole with plastic sheet, holding down the edges with a ring of rocks so that it lies flat. Add some of the soil or sand from the hole to the ring of rocks. This will weigh down the sheet and seal it to the ground surface.
3. Place a rock in the center of the sheet so that it forms a depression directly above the container. Eventually, you will see moisture collecting on the sheet, running toward the middle and dripping in the container.
4. When you've collected enough water in the container, suck it out with the tube. Don't rely on this to keep you alive-it will take all day to obtain enough water for a drink, and you will need more than one drink during this period.

(Adopted from: John Woodward, Necessary Skills and then Some... , New York, Darling Kindersley Limited, 2014.)

What should we do after placing rocks around the plastic?