If it doesn't rain soon, there'll be a great (short). . . . . . of water

1. If it doesn't rain soon, there'll be a great (short). . . . . . of water
2. They haven't found the (solve) ........... to this problem yet
3. We are talking about the preservation of (nature) ................... resources.
4. The plane arrived at the airport (safe) ...................... after a violent storm.
5. You look tired. I think you should (relaxation) ........................ for a while.