A:it's really a nice day today, isn't it?
B:what knid of weather are we going to have today?
C:do you think it is going to rain today?
D:what' it like outside today?
①只能由依法设立的保险公司才能经营
②以人的寿命和身体为保险对象
③是投保人避免风险的有效措施
④以财产及有关利益为保险对象
如图是某同学所画的自制简易净水器示意图.
(1)制作材料:见图标注,则a是____ ,b是____.
(2)使用说明:使用一段时间后,有关物质吸附杂质已达饱和.这时清洗后可以继续使用的是纱布、石英砂和____ ,需要更换的是膨松棉和____.
基因型为AaBbcc的个体与基因型为AaBbCC的个体杂交(符合自由组合规律),则后代中( )