Yes it’s works, thanks a lot:)
Here is the code i’ve used :
$num_comments = get_comments_number();
if ( $num_comments == 0 ) { the_content("Lire la suite"); }
elseif ( $num_comments == 1 ) { the_content("Lire la suite et le commentaire"); }
elseif ( $num_comments > 1 ) { the_content("Lire la suite et les " . get_comments_number( $post_id ) . " commentaires"); }