题型:问答题 简答题 Don't sit on the chair. There _____ on it.A. is some water B. are some waterC. is any water D. are any water 查看答案
题型:问答题 简答题 碳素结构钢以屈服点等级为主划分成五个牌号,即Q195、Q215、0235、Q255和Q275,各牌号钢又按其()由多到少分为A、B、C、D四个质量等级。A.氧、磷含量B.硫、氧含量C.氮、磷含量D.硫、磷含量 查看答案