Greetings, Soufia: You probably want to know about them in the context of Quirk grammar (which sees them in a highly restricted way, I must say), so here's a brief explanation: Adjuncts are more or less integrated into the clause structure. They tells us about space, time, or process (in the broadest sense of the word; plenty of details can be found elsewhere, including on this forum). You can easily think of all those innumerable examples: I found her in the kitchen; He left long ago; They advanced slowly.
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