Since many young people have become rich on Taobao.com, I wonder what        ________ is like to run a successful on-line business.

A．that

B．this

C．it

D．one

在疾病的临床期阶段，采取措施减少疾病危害，防止伤残和促进康复，提高生命质量的预防是（）。

A、二级预防

B、一级预防

C、三级预防

D、整体预防