A:碳笔
B:塑料勺
C:铜线
D:稀硫酸溶液
—Father's Day is coming. Could you tell me ________? —What about a watch? He'll like it.
在物理学中能量的单位是( )
随机掷一枚均匀的硬币20次,其中有8次出现正面,12次出现反面,则掷这枚均匀硬币出现正面的概率是( )