腰椎牵引常取仰卧位,此时卧姿宜为()
A.仰卧,屈曲双髋、双膝
B.仰卧,屈曲单侧髋、膝关节
C.仰卧,腰下垫物
D.仰卧,双腿抬高20°
E.以上均可
参考答案:A
It is illegal for a public official to ask people for gifts or money _______ favors to them. [ ]
A. in preference to
B. in place of
C. in agreement with
D. in exchange for
混凝剂的净水原理是()
A.水解+电中和+吸附
B.压缩双电层+电中和+水解
C.压缩双电层+吸附+架桥
D.压缩双电层+电中和+吸附架桥作用
E.水解+吸附架桥+压缩双电层作用