请将这个穿舱件改成水密的。
Please change this penetrating piece into watertight construction.
只有柚木才能达到橡木的膨胀系数，并保持水密性。
Only teak matches oak's expansion coefficient and stays watertight.
含盐量较低的地表水密度较低，因此下沉和搅动深水的可能性较小。
Less salty surface waters would be less dense and therefore less likely to sink and stir up deep water.
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