After new regulations were brought in last year, planning permission must now be sought for the conversion to an impermeable surface of any area around your house bigger than five square metres.
自去年发布新规定之后，房屋四周改建任何五平米以上的非透水地面都要申请设计许可。
Particularly, the solution for impermeable silt-layer can be used to describe the tidal fluctuation in a confined aquifer under a tidal river separated by an impermeable layer.
特别地，当边界淤泥层为隔水层时，本文的解也可用来描述有潮河流下的承压含水层中的水头波动情况。
Thus clays and shales tend to be impermeable .
因此粘土和页岩就往往不透水。
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