蜗杆传动的失效形式与齿轮传动相类似，其中（）最易发生。
A.点蚀与磨损
B.胶合与磨损
C.轮齿折断与塑性变形
参考答案：A
She likes to have everything in order so that she can ______ them when necessary.
A．have a hand in
B．place hands on
C．put her hands on
D．lay her hand on
对痰液过多且无力咳嗽者。为防止窒息，在翻身前护士首先应
A．给病人吸氧B．给病人吸痰C．指导病人有效咳嗽D．给病人拍背E．慢慢移动病人
