to be she or to be her?

[El10]

The following example is from an exercise in a vocabulary book:
"We thought the actress to be (she/her), but we weren't sure."
Answer: her.
But why is she incorrect? Is it because the verb to be is in its base form?

 

[owlman5]

But why is she incorrect? Is it because the verb to be is in its base form?

Perhaps they object to the use of the subject pronoun "she" after any form of the verb "be". It's certainly normal to say "It's me" when somebody asks who is knocking at the door. "It is I" is pretty stiff and unusual in American English.

People do sometimes say "This is she" on the phone, but I'd say that most sentences sound more natural if you use the object pronoun after the verb "be". I think this is true whether the verb is conjugated or in its base form: Who is there? It's him. (The guy we were waiting for) It is he??? (Grammatically possible, I suppose, but odd and stiff).

 

[velisarius]

"We thought the actress to be (she/her), but we weren't sure."

It's the kind of sentence you are unlikely to meet outside of a text-book exercise.

"We weren't sure" (rather than "we were not sure") indicates informal English, whereas the first clause of the sentence is stiff and unnatural - even with "her". I expect the person who wanted the answer "her" had in mind the mismatch between "weren't" and the more formal "she".

I would say:
We thought the actress was her, but we weren't sure.

 

[El10]

Thank you very much.