--- The young man spent as much time as he _______ the experiments.

--- No wonder he succeeded _______.

A．did; by the end

B．could doing; in the end

C．could doing; at the end

D．could to do; in the end

胡 * * * * 在纪念中 * * 主义青年团成立90周年大会上指出，只有广大青年坚持开拓创新，社会主义现代化事业才能够不断开辟新的发展空间、取得新的突破性进展。开拓创新，我们中学生应该[ ]

①善于观察，敢于想象  

②摆脱定势，求异思维  

③因循守旧，固步自封  

④积累知识，勇于实践

A．①②③    

B．②③④    

C．①②④    

D．①③④