A:保持开花的温度和水分
B:防止花粉成熟后散失
C:防止自花传粉
D:防止外来花粉的干扰
— Did you see Anna after class?
— I saw her leave the classroom, but I didn't notice __________after that.
下列各组物质的溶液相互反应后能产生蓝色沉淀的是 ()
_______ did they watch the 2012 London Oylmpic Games, _______ I watched it.
不法商家在黄金中掺入了铱,损害了消费者的利益。由图中信息可知( )
玲玲在课本中发现了一位同班男同学写给她的纸条,大意是说他很喜欢她,愿意和她交朋友,约她放学后在操场见面。(据此回答题)