It tells you what the paragraph is going to be about.
An F1 hybrid (or filial 1 hybrid) is the first filial generation of offspring of distinctly different parental types. F1 hybrids are used in genetics, and in selective breeding, where it may appear as F1 crossbreed. The term is sometimes written with a subscript, as F1 hybrid.
28 Apr 2014 15:00. A hybrid car is one that uses more than one means of propulsion. At the moment, that means combining a normal petrol or diesel engine with an electric motor. The chief advantages of a hybrid are that it uses less fuel and emits less CO2 than most conventional non-hybrid vehicles.