Here's why:
* Semicolons (;) are used to separate independent clauses that are closely related in meaning.
* Commas (,) have various uses, including separating items in a list, introducing a dependent clause, and setting off introductory phrases.
Correct Usage:
* Semicolon and Comma: You can use a semicolon to separate two independent clauses, and then use a comma within one of those clauses if needed.
* Example: *She went to the store; however, she forgot her wallet, so she couldn't buy anything.*
* Comma Only: Use a comma to separate items in a list or to introduce a dependent clause.
* Example: *She bought milk, eggs, and bread.*
* Example: *Because she forgot her wallet, she couldn't buy anything.*
Incorrect Usage:
* Semicolon before Comma: *She went to the store; however, she forgot her wallet; so she couldn't buy anything.* (This is incorrect because the semicolon should not be used before the comma.)
In short, semicolons and commas have distinct roles, and using them together in the way you described is grammatically incorrect.