— __________.
A:It's my pleasure
B:It doesn't matter
C:Yes, let's go
D:I agree with you
8×____=____
3×____=____
24÷____=____
____÷8=____
若△ABC的三边a,b,c,它的面积为a2+b2-c243,则角C等于( )
操作计算题
绕有线圈的铁心直立在水平桌面上,铁心上套着一个铝环,线圈与电源、电键相连,如图所示.闭合电键的瞬间,铝环跳起一定高度.保持电键闭合,铝环则应____(填“保持原有高度”或“回落”);断开电键时铝环则应____(填“跳起一定高度”或“不再跳起”)