问题
单项选择题
"The ceremony has already started." "Look! The flag（）now."
A.is being raised
B.is risen
C.is being rose
D.is raising
答案
参考答案：A
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"The ceremony has already started." "Look! The flag（）now."
A.is being raised
B.is risen
C.is being rose
D.is raising
参考答案：A
时（T为交流的周期），原线圈中的电流瞬时值为0.03A．变压器的原、副线圈的匝数比为（ ）
：3
表为定积分．