—The light in the office is still on.
—Oh, I forgot _______.
A:turning it off
B:turn it off
C:to turn it off
D:having turned it off
10-1
10-2
10-3
____
10-5
10-7
10-9
11-2
12-9
14-6
15-6
18-9
如图,边长为(m+3)的正方形纸片剪出一个边长为m的正方形之后,剩余部分又剪拼成一个矩形(不重叠无缝隙),若拼成的矩形一边长为3,则另一边长是( )
已知在△ABC中,角A、B、C所对的边分别为a、b、c,b(b﹣3c)=(a﹣c)(a+c),且角B为钝角.
(1)求角A的大小;
(2)若a=12,求b﹣3c的取值范围.