三相半波有源逆变运行时,为计算方便,引入逆变角=()。
A、
B、
C、
D、
参考答案:D
(2013·兰州市高三二模)Look at this year's sales figures ________ last year's; they're much better.
A.against
B.from
C.with
D.between
脑电图诱发试验包括下列哪几项()
A.过度换气
B.闪光刺激
C.剥夺睡眠
D.睡眠诱发
E.药物诱发