sell at half price是什么意思

用法例句

Effective energy of X-ray is generally caiculated by use of half value layer and absorpting coefficient of the absorbing material.

X线的实效能通常由半价层和吸收物质的吸收系数来决定的,半价层则是由X线衰减一半时的吸收物质的厚度而获得的。