It's 11: 00 pm now, but the light in Peter's room is still on. He must have forgotten _______ before going to bed.
A:turn it on
B:to turn it on
C:turning it off
D:to turn it off
规定 acbd =(a+d)(b+c),如果c=﹣1,d=1,a﹣b=23-1,ab=3,那么计算结果是( )
小明在了解了宪法的内容后,说:宪法就是包含了所有法律的总和。你认同小明的观点吗?