—Can I help you?
—_____.[ ]
A. I need your help.
B. Yes, please.
C. I can't help you.
答案:B
甲、乙两同学解方程x2+px+q=0,甲看错了一次项系数,解得根为4和-9;乙看错了常数项,解得根为2和3;则原方程为( )。
什么是降水?什么是降水总量?