英语语法分析

In such a severe circumstance, it has become one of the focuses of operation corporations that how to avoid customer churn and carry out retainment.

在这种形势下，如何防止客户流失、实施客户保持工作，已成为运营商关注的焦点之一。

The main target coal seam of Xieqiao Mine is directly covered with the Quaternary bottom gravels, whose impermeability affects the reasonable retainment of waterproof pillar.

第四纪底砾层直接覆盖在谢桥煤矿煤系地层之上，其隔水性能影响到防水煤柱的合理留设。