单选题 # 为本程序段的功能选择标题 import math def prime(x): n = int(math.sqrt(x)) for i in range(2, n+1): if x%i == 0: return False return True def prime_out(x): for i in range(x,1,-1): if prime(i): print("{:<6}".format(i)) return prime_out(100)