It's almost eight years we _______ each other last time.
A:since; saw
B:before; see
C:after; will see
D:when; have seen
普朗克在1900年将“能量子”引入物理学,开创了物理学的新纪元.在下列宏观概念中,具有“量子化”特征的是( )
x
…
﹣1
﹣ 12
0
12
1
32
2
52
3
y
m
14
−74
﹣2