单词alternate-angles
na.: (一对)错角
网络: 内错角；交错角；内错角相等
（内）错角:
equal angles formed on opposite sides of a line that crosses two parallel lines, in the position of the inner angles of a Z
Alternate Angles: ( mathematics ) Angles like those in the Z shape formed when one line intersects two others
（数学）错角（一直线截另外两直线所成的如Z字形中的角）。