题目

It is known to us that doing eye exercises ________ our eyes, and that is to say, our eyes can ________ doing eye exercises. A. benefits; benefit from B. benefits to; benefit C. benefits from; benfit  D. benefits; be benfited from 答案：A 解析: 略图表法、图象法是常用的科学研究方法。（1）短周期某主族元素M的电离能情况如图1所示。则M元素位于周期表的第_____族。（2）图2是研究部分主族元素氢化物的沸点变化规律的图象，折线c可以表达出第_____族元素气态氢化物的沸点变化规律。两位同学对某主族元素氢化物的沸点的变化趋势画出了两条折线（a和b），你认为正确的是折线_____（填a或b）。