已知一个圆锥体的底面半径为2,母线长为4,则它的侧面展开图面积是______.(结果保留π)
底面圆的半径为2,则底面周长=4π,侧面面积=12×4π×4=8π.
在五轮学说中,黑睛为()
A.血轮
B.气轮
C.水轮
D.肉轮
E.风轮
All the photographs in this book, _______ stated otherwise, date from the 1950s.[ ]
A. unless
B. until
C. once
D. if