听听怎么读 英[prəˈmi:θiəm] 美[prə'miθɪrm] 是什么意思 n. 钷(元素符号为:Pm); 英英释义 promethium[ prəu'mi:θiəm ] n.a soft silvery metallic element of the rare earth group having no stable isotope; was discovered in radioactive form as a fission product of ...