* Noun: This is the most common usage, referring to a long, thin mark made by a pen, pencil, etc. Examples: "Draw a straight line." "The line on the graph represents sales."
* Verb: "Line" can mean to cover something with a layer, often with a protective material. Example: "Line the pan with parchment paper."
* Verb: "Line" can also mean to arrange things in a row. Example: "The players lined up on the field."
* Adjective: "Line" can describe something that is straight or follows a line. Example: "The fence was built in a line."
To determine the part of speech of "line" in a specific sentence, you need to look at how it is used.