下列事例中,目的是为了增大摩擦的是[ ]
A.书包背带做的很宽
B.下雪天,在公路上撒些灰渣
C.机器的转动部分安装滚动轴承
D.给机械部件之间的接触面加润滑油
答案:B
语音震颤增强最常见于()。
A.肺实变
B.肺不张
C.胸膜增厚粘连
D.肺水肿
E.肺气肿
With the development of agriculture, the people_____ village I taught arenow living a happy life.
A.in whose
B.whose
C.in which
D.which