softwood的复数形式怎么拼写？

n.软木材...

The mattress is supported on a softwood frame.床垫用软木材架子支撑着。Softwood trees have thin, needle - like leaves.软材树的叶片纤细, 呈针状.Processing category: Corn, peanut, dried potato grains, chemical raw materials, plastics, wood powder...

softwood的反义词有：hardwood。n.softwood的反义词（软木材）：hardwood。...

softwood的音标：softwood的英式发音音标为：['sɒftwʊd]softwood的美式发音音标为：['sɔftwʊd]...