把方程x2-8x+3=0化成（x+m）2=n的形式，则m、n的值分别是
A.4，13
B.-4，19
C.-4，13
D.4，19
答案：C
It is reported that 70% of people in China are ________ about the food security situation after so many accidents.
A．curious
B．concerned
C．cautious
D．certain
简述中国清代皇家园林的特征。
