计时操作 "M" Subscript, "a" "i" "n" "A" "c" "t" "i" "o" "n" , Baseline , "d" Subscript, "t" , Baseline to dt , left brace, "d" Subscript, "t" "s" , Baseline .length less than 20 : "d" Subscript, "t" "s" , Baseline to "d" Subscript, "t" "s" , Baseline .join left parenthesis, , right parenthesis , "d" Subscript, "t" "s" , Baseline to left bracket, mean left parenthesis, "d" Subscript, "t" "s" , Baseline , right parenthesis , right bracket , right braceMainAction,dt→dt,dts.length<20:dts→dts.joindt,dts→meandts
