sum = 0x = 1n = 1while True:? ?if n > 20:? ? ? ?break? ?sum =?sum?+ x?第一輪運算是sum=0+1,第二輪不是應該是sum=1+2=3么？這與題目所求不同??？怎么解釋呢？? ?x = x * 2? ?n = n + 1print sum