A:软骨层
B:骨膜
C:骨松质内的红骨髓
D:骨质
点M与点F(4,0)的距离比它到直线l:x+5=0的距离小1,则点M的轨迹方程是____
下列词语书写完全正确的一项是( )
—Yes, that might ____ why he didn't do well in the test.