A:①③
B:②③
C:①④
D:②④
— Where's Mr. Yu, do you know?
— Well, it's hard to say. But I saw him a football game just now.
小小书法家(看拼音,写汉字)
lāo
ěr
jiàn
gōu
捕____
鱼____
____起
zòng
sāi
jiè
操____
告____
用甲、乙两种单色光照射同一金属做光电效应实验,发现光电流与电压的关系如图所示.已知普朗克常量为h,被照射金属的逸出功为W0,遏止电压为Uc,电子的电荷量为e,则下列说法正确的是( )