硬膜外麻醉时产生全脊麻的发生率平均约（）
A.0.005%
B.0.01%
C.0.024%
D.O.015%
E.O.045%
参考答案：B
I wish to thank Professor Smith, without _______help I would never have got this far.[ ]
A. who
B. whose
C. whom
D. which
一切生命活动都是起源于水的，人体内的水分一般占体重的（）。
A.60～70%
B.50～60%
C.75%
D.80%
