(2m-3n)(______)=4m2-9n2.
∵4m2-9n2=(2m-3n)( 2m+3n),
∴(2m-3n)(2m+3n)=4m2-9n2.
32岁男性患者,右手示指指甲长期疼痛、隆起,深蓝色,手术取出直径0.8cm肿块,镜下见圆形细胞围绕小血管周围形成袖套样结构,患者最可能是()
A.血管球瘤
B.血管周细胞瘤
C.血管平滑肌瘤
D.上皮样血管内皮瘤
E.毛细血管瘤
Some boys of Class One enjoy music.[ ]
A. listen to
B. listens to
C. listening to
D. listened to