控件，主要是在窗口下用的控件，比较方便编程，简单明了，用于示例的。。。。。(control; widget
major; mostly; principal; chief
wicket; medium; intermediary
relatively; compare with; comparatively
convenient; handy; go to the lavatory; have money to spare or lend
simple and clear; concise and explicit; put in a nutshell; brief and clear
typical examples; give a demonstration)