-- Hello, Jessica! What happened?-- I could not hear you clearly because my mobi

    题型： 单项选择题 难度： 一般
    -- Hello, Jessica! What happened?
    -- I could not hear you clearly because my mobile phone could not receive a good _____.
    [???? ] A. sign
    B. signal
    C. symbol
    D. mark
    答案
    B