古诗赏析 。
                                                                                                                                               伤桃源薛道士
                                                                                                                                                     刘禹锡
                                                                                                                             坛边松在鹤巢空，白鹿闲行旧径中。
                                                                                                                              手植红桃千树发，满山无主任春风。

在图中的〇里填上适当的电表符号，闭合电键S，使灯泡L₁和L₂能同时发光。