Another truly wonderful aspect of the Internet is the way _______ to build social ties.

A．which people use

B．people use it

C．people using

D．in which people use

与全面调查相比，抽样调查的特点有______。

A．工作量小、省时间

B．省费用、低成本

C．准确性高

D．抽样误差可控

E．要消耗大量的人力、物力、财力和时间