prepared gravel 中文意思是什麼
prepared gravel
解釋
備制的礫石-
The cushion layer for the dam is constructed with the material prepared mainly with natural sandy gravel and mixed with proper amount of pebble and coarse sand
大壩墊層料採用以天然砂礫料為主、摻入小石和粗砂以調整級配的方式生產。
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