Why the datatypes in Pandas are different from those in SQL

I am a newbie in SQLite and Python and get in circles in the topic.

I import a SQLite table SQL Table Column Data Type into Python

Using Code

    conn = sqlite3.connect("C:\\SQLite\\aaa.sqlite")
    df=pd.read_sql(sql="select * from C",con=conn,coerce_float=True)

When I check the datatype in Python. Some are Objects

 df.dtypes

WD             float64
Manpower       float64
2nd             object
CTR             object
2ndU           float64
T1              object
T2              object
T3              object
T4              object
T5              object

Do you know why the Python convert some columns from float64 to Object?