腰椎间盘突出经卧床休息及骨盆牵引，症状明显好转，开始下床活动，应采取的保护措施是（）。

A.双拐

B.单拐

C.石膏背心

D.围腰

E.轮椅

At 9 a.m, a hiker was due south of point P. What direction was point P from her position at noon ？（）
(1)From 9 a.m until 11 a.m she walked due east at 2 miles per hour, and from 11 a. m until noon, she walked due north at 3 miles per hour.
(2)At noon, she is exactly 4.5 miles from point P.

A．条件(1)充分，但条件(2)不充分．

B．条件(2)充分，但条件(1)不充分．

C．条件(1)和(2)单独都不充分，但条件(1)和条件(2)联合起来充分．

D．条件(1)充分，条件(2)也充分．

E．条件(1)和条件(2)单独都不充分，条件(1)和条件(2)联合起来也不充分．