Keywords like as and is are often used when what type of context clue used?

Keywords like "as" and "is" are often used when the context clue is a definition or synonym.

Here's how:

* "As" often introduces a definition or explanation of a word. For example: "The athlete was known for his agility, *as* he could move with incredible speed and grace."

* "Is" can also be used to connect a word to its definition or synonym. For example: "The drought *is* a period of abnormally low rainfall."

By using these keywords, the writer provides a direct explanation or equivalent meaning for the unfamiliar word, making it easier to understand.