从设计规定的研究对象中对随机抽出的一部分进行调查，称为

A．普查

B．队列研究

C．病例对照研究

D．抽样调查

E．理论流行病学研究

There _____ be any difficulty about passing the road test since you have practised a lot in the driving school. [ ]

A. mustn't

B. shan't

C. shouldn't

D. needn't