DNA变性时表现为
A．戊糖内C-C键断裂
B．磷酸二酯键断裂
C．N-C糖苷键断裂
D．碱基内C-C键断裂
E．对应碱基间氢键断裂
参考答案：E
How many men does your uncle _____ for him?
A．have worked
B．have to work
C．have working
D．have been working
髌骨软骨软化症的治疗，下列哪项是错误的
A．理疗B．局部封闭C．确诊后应手术治疗D．服用消炎镇痛药E．加强股四头肌锻炼
