Sentence:  In the Steiners have busy lives without visiting relatives only context can indicate whether visiting relatives is equivalent in meaning to paying visits to relatives or to relatives who are visiting them , and in I looked up the number and I looked up the chimney only the meanings of number and chimney make it clear that up <WSD>is</WSD> syntactically a second complement in the first sentence and a preposition followed by its object in the second . 
Meaning of the word marked with <WSD> tags:  be identical to; be someone or something