Autumn is .
A：warm
B：cool
C：hot
D：cold
一字组多词
艳____ ____ 希____ ____
勇____ ____ 敬____ ____
12+1 = 1×(2−1)(2+1)(2−1) = 2 ﹣1；
13+2 = 1×(3−2)(3+2)(3−2) = 3 ﹣ 2 ；
15+2 = 1×(5−2)(5+2)(5−2) = 5 ﹣2．
试求：
