—I can't agree more. Because we often have more than one choice.
A:promise
B:mistake
C:speech
D:decision
“朝为田舍郎,暮登天子堂.将相本无种,男儿当自强.少小须勤学,文章可立身.满朝朱紫贵,尽是读书人.”与这首诗有关系的制度是( )
用化学符号或符号表示的意义填空:
①2个磷原子____;
②Al3+____;
③三个硫酸根离子____
④5个水分子____;
⑤NO2中N元素显+4价____.
⑥氯化亚铁____.