— What does your brother look like?

—           . [ ]

A. He's calm and serious

B. He likes singing

C. He's tall with blonde hair

D. He would like some milk

最常见的恶性原发性骨肿瘤是

A．骨软骨瘤

B．骨肉瘤

C．软骨母细胞瘤

D．骨巨细胞瘤

E．骨髓瘤