Sentence:  The natural anatomical and physiological defensive features of the upper respiratory tract , such as the turbinates of the nose and the cilia of the trachea and larger bronchi , are capable of impinging out the larger particles to which we <WSD>are</WSD> ordinarily exposed in our daily existence . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)