Many students have to______ their hobbies because of their busy school work.

A．stay up

B．put up

C．give up

D．look up

下列哪项不是骨质疏松症的骨骼表现()

A．腰背疼痛或全身骨痛是骨质疏松症的最常见症状

B．骨折的发生可有或无诱因

C．负重能力减弱，活动后常导致肌肉劳损和肌痉挛

D．Ⅰ型(绝经后)原发性骨质疏松症以小梁骨和皮质骨为主，Ⅱ型(老年性)原发性骨质疏松症骨丢失以小梁骨为主

E．Ⅰ型(绝经后)原发性骨质疏松症骨折部位以脊椎骨为主，Ⅱ型(老年性)原发性骨质疏松症骨折部位以脊椎骨和髋部为主