道路交通事故中,在来车方向距事故现场( )m处竖立警告标志,防止其他车辆进入事故现场。
A.100 B.150C.200 D.250
参考答案:A
—Your father’s birthday is coming. Why don’t you get him a pair of glasses?
—_______. Glasses can help him see better.
A.That’s too boring.
B.That’s not creative enough.
C.That sounds great.
D.That’s not necessary.
造成加热炉回火的原因及现象是什么?怎样预防?