试题题干
WORD FORMATION
Complete the following sentence with the proper form of the word in the bracket.
(important) The
of particular metals in the human diet has been realized within the past few decades.
参考答案
试题解析
此处缺少名词。
the是冠词，后跟名词，of是介词，所以空格处应填名词。变important为名词importance。
句意：过去的几十年里，人类意识到了饮食中的特种金属的重要性。