下列电力系统短路故障中，无零序分量的短路是（）。
A.三相短路
B.两相短路
C.两相短路接地
D.单相接地短路
参考答案：A, B
Only when _________ the tea-house _______ it was the same place he’d been in last year. [ ]
A. did he reach; he realized
B. he reached; he realized
C. he reached; did he realize
D. did he reach; did he realize
