题目内容双击单词支持查询和收藏哦～
收藏
纠错
One function of the second paragraph of the passage is to
-
A.raise doubts about fluoride's toxicity
-
B.introduce the issue of fluoride's toxicity
-
C.differentiate a toxic from a nontoxic amount of fluoride
-
D.indicate that necessary knowledge of fluoride remains incomplete
-
E.discuss the foodstuffs that are most likely to contain significant concentrations of fluoride
D显示答案
