能量为2MeV的γ射线源,经过3个半衰期后,其γ射线的能量为()。
A.1MeV
B.0.5MeV
C.0.25MeV
D.2MeV
参考答案:D
孝文帝改革促进了北方民族的大融合,具体措施与表现有 ( )
①穿汉服、说汉语、用汉姓 ②迁都洛阳 ③提倡与汉人通婚 ④胡食、胡服、胡乐等融入汉文化
A.①③
B.①②④
C.①②③
D.①②③④
根据首字母及句意完成单词
1. Liu Xiang is a r star.
2. I have a h body(身体),so I`m very strong.
3. Tom has chicken, tomatoes and carots for d
4. Do you like d ?Yes, I like ice cream very much.