—He is going to France ________ He will stay there for two weeks.
A:on sale
B:on business
C:on show
一 My cousin is a clever boy and he is good at math.
一 So he is.
They solved the problem in the end. Yet I really don't know .
在植物细胞中能够把光能转变为有机物的能量,并称为能量转换器的结构是( )