A．The need for labor helped the invention of machinery in America.
B．The farmers rejected Charles Newbold’ s plow for fear of ruin of their field.
C．Both Europa and America had great need of farm machinery.
D．It was in Indiana that the first chilled-plow was produce

A．They stare at the walls.
B．They collect stamps.
C．They attend evening classes.
D．They do whatever they are interested in.