“日啖荔枝三百颗,不辞长作岭南人”.下列有关荔枝食用部分的叙述正确的是( )
A:属于种子,由胚珠发育而来
B:属于果皮,由子房壁发育而来
C:属于种子,由子房壁发育而来
D:属于果皮,由胚珠发育而来
精子和卵细胞相遇是在( )
My sister ______ goes to bed early because she needs a lot of sleep every day.