由于手电钻具有较强的机动性,因而被广泛应用在多种工作场所。但是要想用普通手电钻在水平面上打出竖直的孔或在墙面上打出水平方向的孔,同时还需知道钻孔的进深情况,是很难准确完成任务的。为了解决这一矛盾,我把“扩展普通手电钻的功能”作为发明课 Because the hand drill has strong mobility, it is widely used in a variety of workplaces. However, if you want to use an ordinary hand drill to drill a vertical hole in a horizontal plane or a hole in a horizontal direction on a wall surface, and you also need to know the depth of drilling, it is difficult to accurately complete the task. In order to resolve this contradiction, I took “expanding the function of an ordinary hand drill” as an invention lesson