Clean water and fresh air are essential
题型：选择题
问题：
Clean water and fresh air are essential for our daily life, _______ we can't live.[ ]
A. by which
B. without which
C. that
D. on which
Clean water and fresh air are essential for our daily life, _______ we can't live.[ ]
A. by which
B. without which
C. that
D. on which