如图是为测量电阻面设计的电路，R_x为待测电阻．R′为保护电阻阻值未知，已知R的阻值，电源E的电动势未知，K₁、K₂均为单刀双掷开关．A为电流表，其内阻不计．18-2是按电路图连接的实物图．测量R_x的步骤为：将K₂向d闭合，K₁向______闭合，记下电流表读数I₁，再将K₂向C闭合，K₁向______闭合，记电流表读数I． 计算R_x的公式是R_x=______．

With the situation worsening between China and Japan, the world’s attention is fixed again on_______ is called the East Asia.

A．which

B．what

C．that

D．it