求助

linju

<img src="attachments/dvbbs/2003-11/2003111118102357584.jpg" border="0" onload="if(this.width>screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.alt=\'Click here to open new window\nCTRL+Mouse wheel to zoom in/out\';}" onmouseover="if(this.width>screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.style.cursor=\'hand\'; this.alt=\'Click here to open new window\nCTRL+Mouse wheel to zoom in/out\';}" onclick="if(!this.resized) {return true;} else {window.open(\'attachments/dvbbs/2003-11/2003111118102357584.jpg\');}" onmousewheel="return imgzoom(this);" alt="" />请问各位
大侠，钣金件扭曲中的发展长度是指的什么，有什么意义。如图中的尺寸4