A：3xy=92
B：x+3y+3=65
C：x-3y-2=32·xy
D：x+yx=52
阅读短文, 选择正确的答案。
The red coat is my mother's. It's very beautiful. The brown jacket is my father's. The blue pants are my brother's. They're new. The orange shorts aye my sister's. She likes them very much. The green socks are mine.
给加下划线的字选择正确的解释。
矩形线圈在匀强磁场中匀速转动，从中性面开始转动180°角过程中，平均感应电动势和最大感应电动势之比（ ）
