A:go shopping
B:play football
C:play the piano
下列关于影响农业生产布局条件的叙述,正确的是( )
Mary says she will give me a call _______ she arrives in London.
如图,抛物线y=x2+bx+c经过点A(﹣1,0),B(3,0).请解答下列问题:
注:抛物线y=ax2+bx+c(a≠0)的对称轴是x=﹣b2a.