Okay, the user wants me to translate "sub-grade" into Japanese. Let me think about the correct term here. "Sub-grade" can have different meanings depending on the context. In engineering or construction, it might refer to the subgrade, which is the layer beneath a pavement. The Japanese term for that is usually "下層" (げそう) or "基盤" (きかん). But "sub-grade" could also be part of a larger term, like "sub-grade pavement" which would be "下層舗装" (げそうふそう).
Wait, the user just provided "sub-grade" as the input. They might be looking for a direct translation. Let me check if there's a standard translation for "sub-grade" in Japanese. In some contexts, it's translated as "サブグレード" (subu-gureedo) using katakana, but that's more of a loanword. However, in technical documents, using the native Japanese term is preferable.
Alternatively, if it's part of a term like "sub-grade soil," it would be "下層土" (げそうつち). But without more context, the safest bet is to use the katakana version "サブグレード" unless there's a commonly accepted native term. However, I should also consider if the user might have made a typo. For example, "sub-grade" could be "subgrade" without the hyphen. But the user wrote it with the hyphen, so I should stick with that.
Another angle: in some cases, "sub-grade" might be used in a non-technical context, like a lower grade or class. Then the translation could be "下級" (げきゅう) or "下位" (げい). But without context, it's hard to tell. Since the user hasn't provided additional information, I should go with the most likely technical translation.
I think the best approach is to provide both the katakana and the native term, but the user asked for just the translation result with no explanations. So I need to choose one. Given that, I'll go with "サブグレード" as the direct transliteration, but also consider if "下層" is acceptable. However, the user might prefer the katakana version. Let me confirm with a quick check. In Japanese technical documents, "sub-grade" is often written as "サブグレード" or "下層". Since the user's instruction is to translate, not to explain, I'll provide "サブグレード" as the translation.
サブグレード