【单选题】Chinese married couples red packets to children and the unmarried during the Chinese New Year.
【单选题】Chinese married couple _____ red packets to children and the unmarried during the Chinese new Year.
【简答题】轴承代号6205表示轴承的类型是()、轴承的内径是()mm。
【单选题】轴承代号 30210 中,轴承的内径是 ( )