Sentence:  `` Unless the oyabun has been working on it '' , he said , then checked himself and added : `` You can tell Kayabashi-san that the back road is in very good condition and will <WSD>be</WSD> quite safe for his party to use '' . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)