What have been the big events that have__________China over the last year 2009?

A．shaped

B．taken

C．stated

D．made

在某通信网中，主台的接收机灵敏度为0.25µV，为扩大通信距离，采用的办法是把主台天线升高，并把主台转发灵敏度调整到0.16µV。