Thawing and refreezing each year, an active layer of soil lies over permafrost.

覆盖在永冻层上方的一层活冻层土壤,每年都会融化和重新冻结.

The problem is that much of that refreezing creates a relatively thin layer of so-called first-year ice.

问题是，重新冻结的冰很大程度上相对较薄，所以被称为“首年冰”。

Effective implementation of parental involvement may experience three different stages: unfreezing stage, implementing stage, and refreezing stage.

有效推动家长参与要经历解冻期、推行期、 巩固期等不同阶段，不可一蹴即至。

The warmer ocean would heat the air above it, which would slow the refreezing of ice in winter, which would in turn become even more susceptible to melting in summer.

温暖的海洋将加热海洋上空的空气，这将减缓冬季冰重新冻结，这反过来使海冰更加容易在夏天融化。