全面检查供电设备,确认电缆沟槽、接触网立柱、水围电杆的()能力。
A.抗洪
B.防汛
C.防洪
D.抗洪
参考答案:C
I don't know who invented ________ telephone, but it's really ________ most wonderful invention.
A.the;a
B./;the
C.a;the
D./;a
已知a+b=3,且a﹣b=﹣1,则a2+b2=( ).