BTX compounds (benzene, toluene and xylene) increased to more than 20% in the gasoline in the 1970's. Domestic oil companies have had a century-long history of research to control the product that comes from refining of crude oil.
(BTX compounds; increased; to more than 20%; T:in the gasoline; T:in the 1970's) (the product; comes; from refining of crude oil) (Domestic oil companies; have had; a century-long history of research to control the product) Context(Domestic oil companies have had,List([102, 133))):(Domestic oil companies; have had to control; the product that comes from refining of crude oil)
Domestic oil companies have had,List([102, 133))
BTX compounds the product Domestic oil companies Domestic oil companies
increased comes have had have had to control
to more than 20% T:in the gasoline T:in the 1970's
from refining of crude oil
a century-long history of research to control the product
the product that comes from refining of crude oil