①学习新知 ②寻医问药 ③休闲娱乐 ④传播谣言
A:①②③
B:②③④
C:①②④
D:①③④
— Can you come to a party on Saturday, Peter?
— Oh, ______I'm already going out, I'm afraid.
I think summer is hot.
如图所示,一只烧杯中装有半杯水,放在水平木板AB上,一束光线竖直向下照在水面上。现在B端下方垫一个小木块C,使木板倾斜一个小的角度,则此时( )