诗歌欣赏。
                                                                                                   移家别湖上亭  
                                                                                                       戎昱
                                                                                    好是春风湖上亭，柳条藤蔓系离情。
                                                                                    黄莺久住浑相识，欲别频啼四五声。

______interesting work it is to teach children!

今年5月12日是我国第七个“防灾减灾日”．下列做法不合理的是（　　）

Many airlines now allow passengers to print their boarding passes online ______ their valuable time.

根据这4种微粒结构示意图，判断下列说法中正确的是（　　）

A．它们都带有电荷     B．它们表示同一种元素

C．它们核外电子排布相同 D．它们都具有相对稳定结构