How can I add attrs in ModelChoiceField?

Hello,Everyone,
I know charField can use

forms.TextInput(attrs={'class' : 'form-control',
}),
or
forms.Textarea(attrs={'class' : "form-control",
                                  'rows' : 3 ,
})

to set widgets

but ModelChoiceField?
I have no idea,Django telled me  "'module' object has no attribute 'ChoiceInput'"
 when i use 
forms.ChoiceInput
and "__init__() got an unexpected keyword argument 'attrs'" when i use ModelChoiceField


Can you help me?
Thank you very much?

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