题目

下列日常使用的工具中，属于费力杠杆的是（ ）A.食品夹B.羊角锤C.瓶起子D.钢丝钳 答案：【答案】A【解析】A．费力杠杆动力臂小于阻力臂，不能省力但能省距离。食品夹支点为手柄尾部的连接处，明显阻力臂大于动力臂，其目的是省距离，方便夹取物品，为费力杠杆，故符合题意；B．羊角锤支点为锤身与物体表面的接触点，动力臂大于阻力臂，为省力杠杆，故不符合题意；C．瓶起子支点假定英语课课上老师要求同桌之间交换修改作文，请你修改你同桌写的以下作文。文中共有10处语言错误，每句中最多有两处。错误涉及一个单词的增加、删除或修改。增加：在缺词处加一个漏字符号（∧），并在其下面写出该加的词。删除：把多余的词用斜线（＼）划掉。修改：在错的词下划一横线，并在该词下面写出修改后的词。注意：1.每处错误及其修改均仅限一词。2.只允许修改10处，多者（从第11处起）不计分。I am the senior student. I appreciate make friends with people and I do my best to be on good term with everyone. But in last week I found that one of my friends told another classmate, saying that she disliked me and that she doesn’t want to be my friend any longer. And by now she started playing a trick on me although I’m fat. I’m kind to him but why can’t she be friend to me? As for losing the discouraged weight, should I don more exercise? Use pills? And do you know any other ways? Please give me some advice.