对于一个绕组有分接开关的多绕组变压器，可只测量带分接开关绕组对一个绕组所有分接头的变压比，而对第三绕组只测（）。
参考答案：额定变压比
------She looks very happy. She ______ have passed the exam.
------I guess so. It’s not difficult after all.
A．should
B．could
C．must
D．might
“血海”既指：______，又指_______。
