Fukuda's visit, three months after he _______ office, is the first to China by a Japanese prime minister since Abe's visit to Beijing.

A．takes

B．took

C．has taken

D．has been taken

由于电火花线切割加工速度比电火花成形加工要快许多，所以电火花线切割加工零件的周期就比较短。