.Although it had been______ struggle for him to finish the experiment, he enjoyed the result with________ satisfaction.

A．the, /

B．a, /

C．a, a

D．/, a

下列市场调查的类型中，( )能够以较少的人力和费用开支，较快地掌握调查对象的基本状况。

A．重点调查

B．典型调查

C．市场普查

D．抽样调查