... stroke, horizontal, vertical, lob, top spin, back spin, Wide- line, middle- line, narrow- line).Every program can be changed automatically (30 seconds/program ... backhand 3-line function(wide, medium, narrow) 8.Six-line function:Forehand (wide line,medium line,narrow line) 3-line shootingBackhand (wide line,medium line,narrow line) 3-line shootingIt is ...