Final answer:
The French phrases 'tout d'un coup' and 'soudain' indicate an immediate, unexpected event and are usually followed by the présent tense or passé composé tense in literature.
Step-by-step explanation:
The words tout d'un coup and soudain typically foreshadow the occurrence of something unexpected or abrupt in French literature. These phrases translate to 'all of a sudden' and 'suddenly' respectively in English, and are often employed to indicate a swift, unforeseen change in a story's events or a character's actions. For example, 'tout d'un coup, il se mit à rire' means 'suddenly, he began to laugh.' Both phrases generate a sense of surprise and urgency, propelling the narrative forward in a dramatic fashion.
These expressions are commonly found preceding an action or event that triggers a significant shift in the plot's direction or the emotional state of a character. As they imply immediacy, they are typically followed by the présent tense or the passé composé tense in French, which corresponds to the simple past or present perfect in English narrative