Answer:
Environmentalists want to keep this from drying.
Where can you add 2 to 11 and get 1?
What loses its head every morning only to get it back every night?
Even if you throw it away, it still comes back.
You fill it and it empties, A metaphor for plenty, Depending on what half you see, It's either full or empty
A Chinese, Indian and a Swiss were going to a party. Who is most likely to bring a plus one?