Answer:
has been practicing the violin all afternoon.
Step-by-step explanation:
A sentence is made up of two components subject and predicate. The subject is the part of the sentence about which the sentence has been written. A predicate is the part of the sentence which talks about the subject. It contains the verb and the object. In the given sentence, 'Amanda' is the subject while 'has been practicing the violin all afternoon' is a predicate.