男性，11岁。因左膝关节及大腿间歇性疼痛、跛行1年就诊。

若确定为股骨头缺血性坏死Ⅰ期，首选的治疗方式是（）

A.全身支持治疗

B.股骨头置换

C.关节减压术

D.卧床制动，保守治疗

E.Chiari骨盆截骨+滑膜切除

They demanded that the books ______ to the school library right away.[ ]

A. should return

B. be returned

C. were returned

D. returned