Exercise：
    Choose the most appropriate choice for each italicized word in the following sentences.
    1.Bidding them adieu we departed.
    A．goodbye
    B．curse
    C．blessing
    D．disguise
    2.The government appointed an ad hoc committee to deal with the emergency.
    A．on purpose
    B．unintentionally
    C．for a particular purpose only
    D．randomly
    3.Late again, Richard? What's your alibi this time?
    A．explanation
    B．excuse
    C．complaint
    D．indignation
    4.Sarah used to work as an ambassdor's attache.
    A．member of a staff with a particular responsibility
    B．leader of a special committee
    C．secret agent working for a special agency
    D．guardian of morals
    5.Your statement They have been walking all day long and they must be hungry may be a priori one because they may well not feel hungry in the least.
    A．reasonable
    B．false
    C．presupposed
    D．irrational
    6.It''s a pity that his ten-year-old child is still unable to speak.He may be suffering from aphasia.
    A．grievance
    B．loss of speech
    C．loss of hearing
    D．failure to communicate