汽车等机动车辆排放出的尾气在太阳紫外线的照射下可形成二次污染物。
二次污染物为()。
A.SO3
B.硫酸雾
C.酸雨
D.硝酸雾
E.光化学烟雾
参考答案:E
I told Sally how to get here, but perhaps I ______for her.
A.had to write it out
B.must have written it out
C.should write it out
D.ought to have writte it out
所谓基准重合原则就是定位基准和工艺基准的重合。