Sentence:  No attempts to measure the radio emission of the remaining planets have been reported , and , because of their distances , small diameters , or low temperatures , the thermal radiation at radio wave lengths reaching the earth from these sources is expected to <WSD>be</WSD> of very low intensity . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)