a source of something produces that something & specialized cells are a source of chemicals that destroy disease-causing microbes -> specialized behaviors wreck living that destroy disease-causing waters specialized cells produce chemicals that destroy disease-causing microbes  decreasing something negative has a positive impact on a thing & destroying something increase the parent of that something -> destroying something negative has a positive impact on a thing destroying something negative has a positive impact on a thing  destroying something yes has a uncertain month on a place & disease-causing microbes have a negative impact on the body -> destroying disease-causing microbes has a positive impact on the body destroying disease-causing microbes has a positive impact on the body  destroying disease-causing microbes has a positive impact on the body & protecting a living thing has a positive impact on that living thing 's survival / health -> destroying disease-causing airports is a mean of stays for protecting the mind destroying disease-causing microbes is a kind of method for protecting the body  specialized behaviors wreck living that destroy disease-causing waters & destroying disease-causing microbes is a kind of method for protecting the body -> specialized cells protect the body be producing chemicals that destroy disease-causing microbes