Generally speaking, _________ main mater
题型：选择题
问题：
Generally speaking, _________ main material for building houses has been concrete, but _________ wood and stone have also been used.
A．the; /
B．/; /
C．the; the
D．/; the
Generally speaking, _________ main material for building houses has been concrete, but _________ wood and stone have also been used.
A．the; /
B．/; /
C．the; the
D．/; the