Each element of Concrete is a piece of an artificial mixture of cement, gravel, sand, and (during mixture, pouring, and forming) water.
(Each element of Concrete; is; a piece of an artificial mixture of cement, gravel, sand, and (during mixture, pouring, and forming) water)
Each element of Concrete
is
a piece of an artificial mixture of cement, gravel, sand, and (during mixture, pouring, and forming) water