A.20 B.25 C.30 D.35
A.上半場(chǎng)和下半場(chǎng) B.奇數(shù)場(chǎng)和偶數(shù)場(chǎng) C.前半場(chǎng)和后半場(chǎng) D.左半場(chǎng)和右半場(chǎng)
A.光電轉(zhuǎn)換 B.電磁轉(zhuǎn)換 C.磁電轉(zhuǎn)換 D.電聲轉(zhuǎn)換