Identify the antecedent, if any, in the following sentence: because rebecca has work this weekend, she needs to sleep-in during the week.

Hey there! :D

An antecedent is something in a pre-existing/previous or late/past time frame. In latin, it means 'going before'. 

For example, 

Antecedents have led me to have to maintain a work out schedule. 

(As in, past events or things that I have done previously to not be in shape, have caused me to want to workout and be in shape) 

Think of the antecedent as a noun that replaces a proper noun. 

It is a noun that refers to a proper noun.

'She' refers to the subject (proper noun) Rebecca, so 'she' is the antecedent. 

I hope this helps!
~kaikers