蜗杆传动的效率一般在()左右。
A、90%
B、(70~80)%
C、50%
参考答案:B
how she was helping to save the environment, she said that she always takes
public transportation.
A.To be asked
B.Asking
C.Being asked
D.Asked
可摘局部义齿间接固位体的主要作用不包括()
A.防止义齿向脱位
B.对抗侧向力,防止义齿摆动
C.平衡作用,防止义齿下沉
D.支持作用,防止义齿下沉
E.分散力,减轻负荷