You cannot put the same shoe on every foot.
The underlined phrase functions as the object of the verb 'put'.
You can test this by using passive voice:Ex: The same shoe was put on every foot (by someone). <subject of the passive verb 'was put'> Silence is one of the great arts of conversation.
The underlined part functions as a subject complement. How to test this? Look at the verb. Any form of the verb BE (am, is, are, was, were) on its own (i.e., it doesn't co-occur with a participle (e.g., is walking, was talking) is a verb that takes a subject complement.
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