A:x= −3±62
B:x= 3±62
C:x= −3±232
D:x= 3±232
下列四组简称中,不表示同一省级行政区的是 ( )
A. doctor B. nurse C. teacher D. farmer E. singer F. writer
⑴ ____ ⑵ ____
⑶ ____ ⑷ ____
⑸ ____ ⑹ ____
____