居中

Say in findings report, the chemical contaminant that exists generally in French household is acerbity salt of formaldehyde, aldehyde, phthalein and DDVP.

调查报告，法国家居普遍存的化学污染物是甲醛、乙醛、酞酸盐和敌敌畏。

The turbulator can be used to improve the centralization of the casing strings, to allow the fluid to form spiral flow, as well as to improve the displacement efficiency.

使用旋流扶正器既提高套管的居度,又对流体进行导流而形成螺旋流,还以提高环空水泥浆对泥浆的顶替效率。