— Smart phones are more and more popular now.
— So they are. But they still ________ too much.
A:pay
B:cost
C:take
D:spend
____ ____ ____ = ____
如图表示分泌蛋白的合成、加工和运输过程,①、②、③表示细胞器,a、b、c表示某些过程.下列说法中错误的是( )
下列变化中,没有新物质生成的是( )