Let's look at your sentences and correct the grammar step by step:
- Original: "Deserts are very windy and dry."
Corrected: The sentence is good! You can keep it as it is. - Original: "Rains are so rare that every drop is very important."
Correction: Instead of "Rains," use "Rain" because "rain" is usually uncountable.
Correct version: "Rain is so rare that every drop is very important." - Original: "Even plants have come up with special ways to save water."
Correction: This sentence is mostly correct. Adding "developed" makes it clearer.
Correct version: "Even plants have developed special ways to save water."
Putting it all together, here is the improved version:
"Deserts are very windy and dry. Rain is so rare that every drop is very important. Even plants have developed special ways to save water."
Great job! Keep practicing.