20. Average year-after-year conditions are toas day-to-day atmospheric conditions are to .

scientists have discovered that hiv does not cause aids by the virus's direct effect on the host's immune cells, but rather through the cells' lethal influence on one another. researchers from the gladstone institutes have revealed that hiv does not cause aids by the virus's

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all matter is made up of atoms

in any element all atoms are the same

elements in a compound are always in a constant ratio: apex