A:100 ml 0.5 mol/L MgCl2溶液
B:200 ml 0.25 mol/L HCl溶液
C:50 ml 1 mol/L NaCl溶液
D:200 ml0.25 mol/L CaCl2溶液
如图是植物细胞和动物细胞的结构示意图,据图回答问题:
一个人站在“本初子午线”上,绝对可以确定他所在的半球是( )
It was late. She opened the door ________ because she didn't want to wake up her grandma.
2NO(g)+2CO(g) ⇌催化剂 2CO2(g)+N2(g) △H=-akJ·mol-1(a>0)
鲁肃为什么与吕蒙“结友”?