A:6357千米
B:6371千米
C:6378千米
D:6336千米
一个基因型为YyRr的精原细胞和一个基因型为YyRr的雌蛙,按自由组合定律遗传,各能产生的精子和卵细胞类型是
I, drink, cake, draw, happy, on, they, present
My name is Alice. Today is my birthday. I am ____My mother and father make a ____for me. There are some oranges ____it. They are my favourite fruit. My friends come to my home with a lot of ____.I prepare (准备) many apples and bananas food for ____ .We talk and share delicious food and ____ Well, where is ____little brother? He sits and ____a picture for us.
下表为探究赤霉素打破休眠对马铃薯苗期生长影响的实验结果,据表分析下列说法不正确的是( )
赤霉素浓度(mg/L)
处理时间(h)
株高(cm)
叶面积(cm2/株)
干物重(g/株)
0
22.8
480.7
4.4
10
1
28.0
648.9
5.5
50
39.8
874.8
6.8
100
31.2
854.1
6.5
6
29.4
648.0
5.1
34.4
633.1
5.3
36.2
471.2
4.3
500克盐水中含有50克盐,那么盐和水的重量比是( )