!! +var+ +exec+ +string+
$lst_tit append$lst_titend$type_both
  $(lst_syntax)append $emph object s1 $emphend to $emph str $emphend</tt>
  $lst_mean 串操作: 把对象 $emph s1 $emphend 接在串 
  $emph str$emphend 的后面. $emph object$emphend 可以是 $emph item$emphend,
  $emph word$emphend 或 $emph line$emphend. $emph s1 $emphend should not be empty before evaluation.

