带电粒子通过物质介质时,单位路径形成的离子对数目称()
A. 电离
B. 激发
C. 电离本领
D. 电离密度
经纬仪测角中,其操作步骤之一是调节()使十字丝分别清晰。
A. 目镜
B. 物镜
C. 对光螺旋
D. 反光镜
The key of the reduction of salt intake is__________.
A. salt is all inerrant flavor enhancer and preservative
B. salt is an essential nutrient for the body
C. the businessmen worry they will get less profit
D. there are some other important factors for high blood pressure