Mary ______ all the housework, she dropped herself into the sofa, sighing with relief.

A．finished

B．had finished

C．having finished

D．finishing

男，10岁。突然发热，伴左大腿内下部持续性剧痛半个月，拒按，膝关节不肿，无压痛，浮髌试验阴性。白细胞计数增加。X线检查见股骨下端骨破坏，其诊断是（）

A.急性化脓性骨髓炎

B.类风湿关节炎

C.化脓性关节炎

D.股骨头缺血性坏死

E.急性脓肿