下列关于强直性脊柱炎的说法哪项不正确
A.本病病因不明B.严重者全脊柱可发生融合C.易发双髋关节破坏D.下肢肌肉常萎缩E.治疗以手术为主
参考答案:E
They were all so tired that they could ______. [ ]
A. do nothing but sleep
B. do anything but sleep
C. do nothing but to sleep
D. do anything but to sleep
辐射剂量只要控制在可接受的指导水平即可,不需要考虑是否达到最优化。