题目

The roads into London were so _____ traffic that even the fire engines couldn’t get through. A. choked up by                                       B. choked up with     C. choked back by                                     D. choked back with 答案：B二次函数y=x 2 +5x+4，下列说法正确的是（ ）A. 抛物线的开口向下 B. 当x＞3时，y随x的增大而增大C. 二次函数的最小值是2 D. 抛物线的对称轴是x=