Based on 4d, ex.5

Fill in: in, at, on.

1. We spent hours gazing
   [ ]
   the pretty stars in the night sky.
2. We have an environmental awareness day
   [ ]
   my school.
3. Don't leave the light
   [ ]
   when you're not in the room.
4. The enclosure is five metres
   [ ]
   length.
5. Sadly, many people have difficulty
   [ ]
   practising the three Rs: reduce, recycle, reuse.
6. On a compost heap, you put new material
   [ ]
   top of older material.