如果是我，我想将date2/time3合并为一列，将date4/time5合并为一列，如:

If it were me, I'd want to combine date2/time3 into one column, and date4/time5, as in:

df['date2'] = (df['date2']+'T'+df['time3']).astype('datetime64')
df['date4'] = (df['date4']+'T'+df['time5']).astype('datetime64')