Sentence:  In I 'll go with George dominant stress is probably on George ; but if George has just been mentioned prominently ( and the trip to be made has been under discussion ) , what is said is probably I 'll go with him , and dominant stress <WSD>is</WSD> probably on the preposition with . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)