A:①②③④
B:③①④②
C:③①②④
D:④②①③
—The firemen did all their best to put out the fire.
— excellent firemen!
a蓝藻;b绿藻;c发菜;d念珠藻;e颤藻;f紫菜;g硝化细菌;h酵母菌;i链球菌;j噬菌体;k青蛙;l蘑菇
m支原体n衣原体.
如图,在△ABC中,M是BC边的中点,AP是∠BAC的平分线,BP⊥AP于点P. 若AB=12,AC=22,则MP的长为( )