A:3
B:﹣3
C:13
D:﹣13
下列词语中,书写完全正确的一项是( )
下列图形中是旋转对称图形的有( )
①正三角形 ②正方形 ③三角形 ④圆 ⑤线段.
分式xy2ab 、xx-ybc、-yx+yac2的最简公分母是( )
After you learn about the lives of the pilots, especially their hard training, you can decide ______ you want to become a pilot or not.