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来源:雅诚德英语网
Think of the pitch of a siren on an ambulance, which goes from high to low as it passes the observer.
试想救护车上的报警器,经过观测者的时候,其音调会呈现出由高到低的变化。
Think of the pitch of a siren on an ambulance, which goes from high to low as it passes the observer.
试想救护车上的报警器,经过观测者的时候,其音调会呈现出由高到低的变化。