The students entered the classroom, smiling and________, and________down to have their lessons.  [      ]

A. talked; sat  

B. talking; sitting

C. talking; sat  

D. talked; sitting

骨结核与骨髓炎鉴别的说法正确的是

A．骨结核病程长于骨髓炎

B．骨结核死骨比骨髓炎大而常见

C．骨结核比骨髓炎较多发纤维性关节强直

D．骨结核与骨髓炎均可引起软组织肿胀

E．骨髓炎骨质破坏伴硬化少、结核硬化多