一元二次方程x2+x-2=0的根的情况是( )
A:有两个不相等的实数根
B:有两个相等的实数根
C:只有一个实数根
D:没有实数根
根据句意和汉语注释,写出单词的正确形式。(1)Guangdong is in the ____ (north) part of the city(2)She danced so ____ (beauty) that everyone clapped their hands.(3)Look! Their____ (wife) are waving to them(4)Do you think noise ____ (pollute) is a terrible problem?
在极坐标系中,若直线l的方程是ρsin(θ+π6)=1,点P的坐标为(2,π),则点P到直线l的距离d=____
2Hg(l)+O2(g)=2HgO(s);△H=﹣181.6kJ•mol﹣1
则反应Zn(s)+HgO(s)=ZnO(s)+Hg(l)的△H为( )