Most environmental problems exist because
题型:单项选择题
问题:
Most environmental problems exist because adequate measures for preventing them______ in the past.
A.was not taken
B.were not taken
C.didn't take
D.haven't taken
Most environmental problems exist because adequate measures for preventing them______ in the past.
A.was not taken
B.were not taken
C.didn't take
D.haven't taken