The phrase "are mostly water" is correct and usable in written English.
It can be used when discussing the composition of living organisms, particularly in a scientific or educational context.
Example: "Humans, like many other living beings, are mostly water, which is essential for various biological functions."
Alternatives: "primarily composed of water" or "largely made up of water".
The particles are mostly water ice, but the presence or absence of other elements and molecules will tell something about the inside of Enceladus.
Foods that are mostly water, like watermelon, which is 98percentt water, can also be a help as long as they are not too rich in carbohydrates or salt.
"A lot of kids are reaching for energy beverages instead of sport drinks, which unlike the energy drinks are mostly water with a nominal amount of sugar and electrolytes," he said.
Astronomers have discovered a new planet in our galaxy that is unlike any other found so far: Both the planet and its atmosphere are mostly water, though none of it is liquid.
The gas industry counters that fracking takes place too far below aquifers for contamination to take place, and that chemicals compose, by volume, less than 1 percent of fracking fluids, which are mostly water and sand.
Since all living things are mostly water, why don't plants freeze solid and die? A. Sometimes they do die, but that mostly happens when people push their luck and try to grow something that isn't hardy in their area, or when winter becomes extraordinarily cold for an extended period or shows up too early.
As the mature carbonate reservoirs of the Middle East are mostly water-flooded, the microemulsions designed for them are a water external system (Winsor Type I) with oil solubilized in the core of the micelles.
Contrary to the rest of the proteins, which are mostly water-soluble and can easily be analyzed using EC techniques, membrane proteins are poorly soluble or insoluble in aqueous solutions and/or unstable outside the lipid membrane.
(Wine is mostly water, and thus can also douse flames).
Being mostly water, jellyfish react strongly and quickly to all of these changes.
Fruits and vegetables provide essential vitamins and minerals, but they're "mostly water".
