Final answer:
Signal words and phrases are used to indicate shifts in ideas or relationships in a text. In the phrase 'left over and tracers,' there are no specific signal words or phrases. However, in a sentence or paragraph context, signal words like 'but' or 'however' may indicate contrast or opposition.
Step-by-step explanation:
In the context of language and writing, signal words and phrases are used to indicate a shift in ideas or the relationship between different parts of a text. In the phrase 'left over and tracers,' there are no specific signal words or phrases as the phrase itself does not provide any context. However, if we were to analyze a sentence or paragraph containing these words, we might find signal words like 'but,' 'however,' 'on the other hand,' or 'in contrast' to signal a contradiction or opposition.
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