化学用语的学习化学的重要工具,下列对化学用语的叙述或使用正确的是( )
A:N-3H3﹣﹣NH3中氮元素的化合价为﹣3价
B:4H﹣﹣4个氢元素
C:镁离子﹣﹣Mg2+
D:氧化亚铁﹣﹣Fe3O4
Today is Monday. Linda is at school. She has Chinese,English and PE in the morning. She doesn't have Music today. She has Maths and Art in the afternoon. She has Music on Fridays.
把下面句子按顺序排列。
①世界上最辉煌壮丽的建筑群,顷刻之间就被毁灭了。
②霎时间,烈焰腾空,浓烟滚滚。
③洗劫、捣毁之后,强盗们还不罢休。
④烟灰和一阵阵劈劈啪啪的响声过后,整个圆明园成了一片废墟。
⑤他们骑着马分头在圆明园内各处放起火来。