A:c⊥α,b∥β,α⊥β
B:c⊥α,b⊥β,α∥β
C:c⊂α,b⊥β,α∥β
D:c⊂α,b∥β,α⊥β
正比例函数y=﹣k2x(k≠0),下列结论正确的是( )
小宇想测量他所就读学校的高度,他先站在点A处,仰视旗杆的顶端C,此时他的视线的仰角为60°,他再站在点B处,仰视旗杆的顶端C,此时他的视线的仰角为45°,如图所示,若小宇的身高为1.5m,旗杆的高度为10.5cm,则AB的距离为( )
Read and Judge.读短文,判断表格中的单词是对是错。
Hello. I am a boy. My name is Jack. I carry my bag and go to school. 1 have a pendl-case. Open my pencil-case. I have a pen, pencil, and shmpener ( 削笔刀). And the books are in the bag.