Final answer:
Contractions, slang, and casual language should be avoided in formal writing assignments.
Step-by-step explanation:
You should avoid using contractions, slang, and casual language in formal writing assignments. This is true because formal writing requires a more professional and academic tone. Contractions, slang, and casual language are often considered informal and can undermine the credibility and clarity of your writing. For example, instead of saying 'can't' in formal writing, it's more appropriate to write 'cannot'.
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