modern periodic chemical, chemical modem periodic, modem chemica

modern periodic chemical, chemical modem periodic, modem chemical periodic; know, knew, known Dmitri Mendeleev is considered the "father" of the______table. He wrote out the names, atomic masses and other properties of each_______elements on separate cards. Then, he ordered them according their atomic mass.
【正确答案】：modem chemical periodic；known
【题目解析】：modem chemical periodic table的意思是“现代化学元素周期表”，known表示“已知的”。