单相半控桥整流电路的两只晶闸管的触发脉冲依次应相差 ________ 。

A、<span style="font-size:14px;font-family: &#39;Times New Roman&#39;,&#39;serif&#39;">180</span><span style="font-size:14px;font-family:宋体">°</span>

B、<span style="font-size:14px;font-family: &#39;Times New Roman&#39;,&#39;serif&#39;">60</span><span style="font-size:14px;font-family:宋体">°</span>

C、<span style="font-size:14px;font-family: &#39;Times New Roman&#39;,&#39;serif&#39;">360</span><span style="font-size:14px;font-family:宋体">°</span>

D、<span style="font-size:14px;font-family: &#39;Times New Roman&#39;,&#39;serif&#39;">120</span><span style="font-size:14px;font-family:宋体">°</span>