Distortion Phenomenon Analysis of 3m Ruler Used in the Test of Hot Surface Smooth

　　3m直尺用于熱鋪層平整度檢測時(shí)的熱變形現象分析

　　The teacher came in and a ruler was in his hand.

　　老師走進(jìn)教室，手里拿著(zhù)一把直尺。

　　Take out a ruler draw a line.

　　拿出直尺，畫(huà)條線(xiàn)；

　　Proportional servo valve, grid ruler and CNC machine tool

　　伺服比例閥、光柵直尺與數控機床

　　At breast height, measure the trunk diameter by a ruler.

　　在胸部高度的位置，用一把直尺量度干徑。