sentences: chlorophyll is used for absorbing light energy by plants
docs: chlorophyll is pigment. chlorophyll is green. leaf is device_for_absorbing_light. chlorophyll is chlorophyll. chlorophyll is chemical. bacteriochlorophyll is photosynthetic_pigment. chlorophyll_b is photosynthetic_accessory_pigment. chlorophyll is photosynthetic_pigment.