我已经预先清理了数据，下面显示了前4行的格式：
[IN] df.head()
[OUT] Year cleaned
0 1909 acquaint hous receiv follow letter clerk crown...
1 1909 ask secretari state war whether issu statement...
2 1909 i beg present petit sign upward motor car driv...
3 1909 i desir ask secretari state war second lieuten...
4 1909 ask secretari state war whether would introduc...
我已将train_test_split（）称为如下：
[IN] X_train, X_test, y_train, y_test = train_test_split(df['cleaned'], df['Year'], random_state=2)
[Note*] `X_train` and `y_train` are now Pandas.core.series.Series of shape (1785,) and `X_test` and `y_test` are also …