【简答题】如图所3号发光二极管的正极是( )端,负极是( )端。(备注:括号里选填e、f)
【单选题】飞机着陆时必须保持( )和跑道方向一致。
【简答题】An Englishman was once traveling in Italy. One day he went into a small restaurant to order dinner. He understood very little Italian and couldn’t read the menu(菜单). He knew the word for eggs, and so ...
【判断题】数字万用表识别发光二极管的正负极时,如果LED灯亮了,则红表笔所接的引脚是发光二极管的正极,黑表笔接的是负极。
【简答题】根据结构特点,疑问句可以分为是非问、()、选择问和正反问。