A:has been bought
B:will be bought
C:is bought
D:was bought
下列哪种昆虫的发育过程要经过卵、若虫、成虫三个阶段( )
某科研小组用不同浓度的脱落酸处理同种水稻种子,在相同条件下培养后测得秧苗的干重和鲜重情况如图.下列有关叙述正确的是( )