Fill in the Blanks (Reading & Writing)

Modern recycling plants sort household waste using a —combinationcombinecombiningcombined of magnets, sensors and manual inspection to separate metals, plastics and paper. Materials that cannot be —economicallyeconomiceconomyeconomics recovered are diverted to landfill, while the rest is compressed into bales for resale. Efficient sorting depends —heavilyheavyheavinessheavier on residents rinsing containers beforehand, since contaminated items often —spoilspoiledspoilingspoilage an entire batch and force it to be discarded.