地球仪上0°纬线的长度是0°经线的( )
A:0.5倍
B:1倍
C:1.5倍
D:2倍
已知:x+y=﹣3,x﹣y=7.
求:①xy的值; ②x2+y2的值.
Time of the accident
Last week.
Place of the accident
On my way to Li Ming's ____.
Reason and result of the accident
I rode too ____. My bike hit a big tree. I was in a lot of ____.
Aid
A passerby ____ me to the ____.
如图表示细胞中各种化合物或主要元素占细胞鲜重的含量.①②③④依次为( )