A:资源的有效性与人类需求的无限性
B:局部利益与整体利益
C:个人行为和大众利益
D:短期经济利益与长远环境效益
①二次三项式ax2+bx+c的最大值为4;
②4a+2b+c<0;
③一元二次方程ax2+bx+c=1的两根之和为﹣1;
④使y≤3成立的x的取值范围是x≥0.
其中正确的个数有( )
Many fast food restaurants paint their walls red, play loud music and have hard seats_____ customers eat quickly and leave.