What structure and rhetorical style does the author use in the letter to the editor of the daily news?
compare/contrast with an emotional appeal
sequential order with a scientific appeal
problem/solution with a logical appeal
cause/effect with an ethical appeal

a polymer is a chainlike molecule made up of small molecular units. these small molecular units are called monomers. monomers of polymer can be joined together either naturally or synthetically.  

for  example, forests have higher evapotranspiration than other ecosystems,  such  as grasslands, because of their deeper roots and greater leaf area. thus forests have a net moistening effect on the atmosphere and become a moisture source for downwind ecosystems.