【简答题】Today, roller-skating is easy and fun. But a long time ago, it wasn’t easy at all. Before 1750, no one had any ideas of roller-skating. That changed because of a man named Joseph Merlin. He liked to m...
【简答题】A: Why isn't it easy to solve the problem? B: Because water is far ____ than energy. No other ____ water, so it is impossible to find ____it. Besides, water demand is rising, but water supply is fluct...
【多选题】湿作业灌注桩成孔质量检查的主要内容包括( )。
【多选题】如何判别一个发光二极管的极性?
A.
直插式发光二极管 , 长脚为正极 , 短脚为负极 。
B.
直插式发光二极管 , 长脚为负极 , 短脚为正极 。
C.
用数字万用表的二极管检测档位 , 用表检测时若表有读数 , 同时发光二极管发光 , 则红表笔所测端为二极管为正极 。
D.
用数字万用表的二极管检测档位 , 用表检测时若表有读数 , 同时发光二极管会发光 , 则红表笔所测端为二极管为负极 。
【单选题】使用数字万用表时,下面操作方法不正确的是
【简答题】It is easy to repair a car if you have the necessary———. 2. Last year Europe suffered a really———-winter which closed a lot of airports. ...
【多选题】湿作业灌注桩成孔质量检查的主要内容包括( )。