...there is no water supply. I bring some water.

\(\dfrac{5}{9}\times\dfrac{8}{17}+\dfrac{4}{9}\times\dfrac{8}{17}=\dfrac{8}{17}\times\left(\dfrac{5}{9}+\dfrac{4}{9}\right)=\dfrac{8}{17}\times\left(\dfrac{5+4}{9}\right)=\dfrac{8}{17}\times\dfrac{9}{9}=\dfrac{8}{17}\times1=\dfrac{8}{17}.\)

\(210:\dfrac{25}{12}=\dfrac{210}{1}:\dfrac{25}{12}=\dfrac{210}{1}\times\dfrac{12}{25}=\dfrac{210\times12}{1\times25}=\dfrac{2520}{25}=\dfrac{504}{5}.\)

11. returned

12. thought

13. went

14. have driven

15. arrive - had been

16. asked - had

17. said

18. told

19. walked

20. saw

21. stopped - bought

22. was.