In [6]:#第三题 year = int(input(' year : \n'))month = int(input ('month: \n'))day = int(input(' day : \n')) months = (0,31,59,90,120,151,181,212,243,273,304,334)if 0 < month <= 12: sum = months[month - 1]else: print (' data error')sum += day leap = 0 if (year % 400 == 0) or ((year % 4 == 0) and (year % 100 != 0) ) :leap = 1 if (leap -= 1) and (month > 2):sum t= 1 print ('it is the %dth day.' % sum) 修改为正确格式

可以将其修改为如下格式：

year = int(input('year: \n'))
month = int(input('month: \n'))
day = int(input('day: \n'))

months = (0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334)
if 0 < month <= 12:
    sum = months[month - 1]
else:
    print('data error')

sum += day
leap = 0
if (year % 400 == 0) or ((year % 4 == 0) and (year % 100 != 0)):
    leap = 1
if (leap == 1) and (month > 2):
    sum += 1

print('it is the %dth day.' % sum)

注意要使用正确的缩进和语法格式，同时还需要将字符串中的引号统一使用单引号或双引号。此外，还需要修复代码中的语法错误，比如 `if` 语句中的条件判断应该使用 `==` 而不是 `-=`。