1、将一个字典输入：
该字典必须满足：value是一个list类型的元素，且每一个key对应的value长度都相同：
（以该字典的key为columns）
>>> import pandas as pd
>>> a = [1,2,3,4,5]
>>> b = ["a","b","c"]
>>> c = 1
>>> df = pd.DataFrame({"A":a,"B":b,"C":c})
Traceback (most recent call last):
ValueError: arrays must all be same length
>>> df = pd.DataFrame([a
