The second semantic meaning of this URI applies when the original transport-specific back channel is not available (for example, the connection was broken).
此 URI 的第二个语义含义则是在原始传输特定回发通道不可用时发挥作用（例如，连接已断开时）。
The usage of metaphor is in connection with the fundamental change of speech in the semantic field, which can make people realize the literal meaning of the speech and also its figurative meaning.
比喻用法涉及言语在语义场的根本变化，使人既能意识到言语的字面的意义，又能意识到它的比喻意义。
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